




> 























o * 

\'' .. -^ 



-^0^ 



J^ o 




■^ .f- V^ii-."-^. c°*.c^.*-o /-a^i-** 






A 



^oV 



-T) 











Ao^ 



o V 




*« 



■ G^ \5 'o . » « A 







-^ 4. . • ^ 



v-^^ 



•j^s- 







"^ov :^o 











^°-n^. 





O^ « . O v"^ , , , • 0,-V- 

'^ ..^'•' *A\R//%'= "^-^ ^^"^ *'* 
* 4^ -^^ •, 







AfA: 



V .^i.:^'. 




,\' 


















: "V/ 



















,v ^^ 









.o-*. 







'bV" 





i.i^'' ■> e.'' "^ ° WWW * A^-^ 








^"^^ 




V"^-\/^ v^^*'/' X^^^"\/., "^ 

•'■-■• '°- / -^^ Z.:^^- "-^ ./.-^i--^^ '°-'<^^-> /--^i-X .^"'^(fe-^ / 





■''^0^ 



"oV" 




''^o^ 



^* . 1 ' 



.<»' 



* ^v 



cv * 




^oV' 



V'"^'^'*/ 'V*^*\^^ "^^^''^^'Z A> - ^^ 











"^•'' .^'*^ 







V ,^ 










* .V 




^^v 




v^ .^r^L' 





"-^ /,-^;A 'f4mi:°-^ ./.-^i^^ ^°'*^a.-> .^* -^i-^-* ^°-:^^-> / 

,0 % 



cv * 










^°-'*. 












^^ A^ 



^ A 



.^^i^. 














< V -i> " « " A 



<^, '^ 



■^^ V \ 




'""^ -^^ oo\y;^^"°o /\.a^:A c°'.y^^% .<.^i.\ ^'^:km;> /^•^i'\.^^ 












A<^^ 




\0 .:•=' 



c^ 






<5^. 



.V 



'o- ^^ 






• ^^^.c.-^ /A^lfA^o ^-j-.A^ ;, 



%.a'' 






"^^^ '^mmr. ■ '\^^_™^ 



U.S. Department of the fnteribr 
Bureau of Mines 




\ 




EALTH 

Morih 1981 



HIGHLIGHTS: 

i SAFETY «SE)nt£iir 1970-8 







Under provisions of the Federal Coal 
Mine Health and Safety Act of 1969, and 
the Amendments Act of 1977, the Bureau 
of Mines is conducting research to 
improve the health and safety of workers 
in the minerals industries. This docu- 
ment presents an overview of selected 
accomplishments implemented 
Bureau's Minerals Health 
Program. 



through the 
and Safety 




Technical Highlights 
Bureau of Mines 
Health and Safety 
Research Program 
1970 - 1980 







J. 



This publication has been cataloged as follows: 



United States. Bureau of Mines 

Technical highlights, health and safety research, 1970-1980. 



(Special publication) 
Supto of Docs- no.: I 28.151. 
1. Mine safety-United States. I. Titlcj, 
publication. (United States. Bureau of 



ies: Special 



TN295.U5 




Executive Overview 1 

Health 8 

Accident Prevention 44 

Disaster Prevention 95 

Summary Tables 133 






EXECUTIVE OVERVIEW 



Background '. .'. .*?;. i ,• - • < . 

Program Emphasis. 2.' " .ij' ; •. ". 

Program .Interaction. . . .4 ■ ' ":*-■ " - * -' . 
Techno! ogy. Trarrs fer. . .^ ^%.,; - a^' *V 
Program Effecti venes.s. .^ ■•• - ♦V*'-#. 
Future Needs . . .; .♦;.■.■ :^ .'C>. '-".Z^- 



Concluding Remarks ,,.,.. ,»J 



■^f^- 






\ 



BACKGROUND 



Since its inception in 1910, the Bureau of Mines 
has addressed the problems of disease and injury in 
mining. In the last decade (1970-80), however, 
there has been an increased awareness of the need 
to improve the working conditions in the minerals 
industry; as a result, the Bureau has been given 
increased responsibility and funding to address the 
problems. A significant expansion of research 
occurred with the passage of the Federal Coal Mine 
Health and Safety Act of 1969 (Public Law 91-173), 
which directed the Bureau to conduct research and 
development activities to eliminate coal mining 
hazards and/or provide alternative methods of 
accomplishing the required mining operations more 
safely. Subsequently, Congress enacted the Federal 
Mine Safety and Health Amendments Act of 1977 
(Public Law 95-164), which for the first time 
provided one piece of comprehensive legislation 
that covered coal as well as metal /nonmetal mining 
operations. While this legislation provided for 
increased regulatory activities, principally in 
metal /nonmetal mines, it also significantly in- 
creased the funding available for research and 
development to address the problems in all segments 
of the mining industry. 

This report highlights some significant results 
from the Bureau of Mines Minerals Health and Safety 
Technology Program that are currently available for 
use, together with other developments that have 
been, or will be demonstrated in operating mines in 
the near future. Notable achievements have been 
made in most areas of health and safety, and many 
more functional devices and techniques are expected 
to be available within the next two years. 



The successful results of the Minerals Health and 
Safety Technology Program would not have been 
possible without the active participation and 
cooperation of many mine operators and equipment 
manufacturers. The participation of these organi- 
zations has been extensive as evidenced by the 81 
mining companies and other organizations having 
Memorandums of Agreement with the Bureau's Division 
of Minerals Health and Safety Technology in 1980. 
In addition to these agreements, approximately 500 
agreements were in effect between the industry and 
Bureau contractors that are developing and/or 
demonstrating mining-related technology. 

The Bureau also works in conjunction with specific 
industry groups such as the American Iron Ore 
Association, the National Industrial Sand Associ- 
ation, and Bituminous Coal Research Incorporated, 
an affiliate of the National Coal Association. A 
cooperative program with the American Iron Ore 
Association, established in October 1976, is di- 
rected at the development and demonstration of 
noise control techniques for application in taco- 
nite processing plants. The Association has made 
available to the Bureau and its contractors numer- 
ous plants for an in-depth analysis of the magni- 
tude and source of noise generators. Cooperative 
work with the National Industrial Sand Association 
is directed toward the development of control 
measures and improved personal protection for 
silica bagging operations. Although notable pro- 
gress has been made in reducing personnel exposure 
to respirable dust, additional work is necessary 
(and ongoing) to bring these plants into compliance. 



Bituminous Coal Research, Incorporated (BCR), 
represents coal companies responsible for about 
half the coal production in this country. Through 
cooperative projects. Bureau-funded contracts, and 
cost-sharing contracts, BCR has been the coal 
industry's liaison in the successful implementa- 
tion of a number of Bureau-industry programs. The 
participation of the minerals industries in this 
program has been noteworthy, and it is anticipated 
that this cooperation will continue to grow, thus 
accelerating the implementation of efforts to make 
the minerals industries safer and more healthful. 

The Bureau interacts with and has the input and 
participation of many other organizations, domesti- 
cally and around the world. A recent count shows 
that the Bureau interacts with over 26 governmental 
or international organizations in the implementa- 
tion of the program. These agencies either provide 
input to or derive benefits directly from the 
program. The three principal agencies with whom 
the Bureau interacts are the Mine Safety and Health 
Administration (MSHA), the National Institute of 
Occupational Safety and Health (NIOSH), and the 
Fossil Energy Program of the Department of Energy 
(DOE). Without this participation the program 
described herein would not have been possible. The 
Bureau has formal agreements with seven foreign 
nations on the exchange of hardware and technology. 
The largest and most active of these agreements is 
with the National Coal Board of the United Kingdom. 

PROGRAM EMPHASIS 

The Bureau's program for improving mine health and 
safety is categorized into the areas of Health, 



Accident Prevention, and Disaster Prevention. One 
activity. Systems Engineering, is common to all 
these areas and is not listed below. Within the 
three areas, the program activities are as follows: 

HEALTH 



t 


Respirable Dust 


• 


Noise 


t 


Ventilation 


• 


Industrial Hygiene 


• 


Radiation 


ACCIDENT PREVENTION 


• 


Ground Control 


• 


Industrial Hazards 



DISASTER PREVENTION 

t Fire and Explosion Prevention 

• Explosives 

• Methane Control 

• Postdisaster, Survival, and Mine Rescue 

Within the Health area the Bureau has developed 
unique competence and expertise in the area of 
control technology related to health hazards asso- 
ciated with minerals processing and extraction. 
The Bureau's research activities do not involve the 
medical aspects or epidemiological studies that are 
associated with health problems in the minerals 
industry. These types of studies are conducted by 
the National Institute of Occupational Safety and 
Health which also conducts, on occasion, in-mine 
assessments of health hazards and/or the effective- 
ness of control technologies. There is some joint 
work in the area of instrumentation for the meas- 
urement of health hazards, such as better respirable 



dust meters. The interplay of NIOSH activities 
with the Bureau program is noteworthy in the over- 
all goal of insuring the health of this country's 
miners. The combined efforts of both agencies seek 
to provide solutions to the principal health-rela- 
ted problems of the minerals industries. 

Interaction with the Department of Energy (DOE) has 
continued since its formation in 1978. The liaison 
was facilitated by the fact that the DOE mining 
program was developed and managed by the Bureau 
until its transfer to DOE. In fiscal year 1979 the 
Bureau conducted approximately $1 million of health 
and safety projects identified and funded by DOE; 
additionally, the Bureau was managing $2.2 million 
of DOE methane drainage research, which is comple- 
mentary to the Bureau's methane drainage work. 

The emphasis and direction of each of the 11 re- 
search areas are briefly characterized in the 
following sections of this report. Funding levels 
for general research areas are adjusted as required 
to accommodate changes in priorities based on total 
input from the mining community and in the relative 
difficulties encountered in implementing satisfac- 
tory solutions. Priorities for project funding 
within a research area are established primarily 
through joint Bureau and MSHA committees that meet 
on a regular basis. The funding levels for the 
research areas and the adjustments made in the 
past three years are shown in the graph. 

As indicated above. Health and Safety Program 
funding has increased over the last decade as a 
result of Congressional recognition of the need for 
increased and accelerated emphasis in this area. 




ACCIDENT 
PREVENTION 



DISASTER PREVENTION 



However, the adverse inflationary impact on these 
resources is also noteworthy, because the purchas- 
ing power of the program budget of $60 million in 
1980 has hardly kept pace relative to even the $30 
million budgeted in 1972. 

Health and safety research has been characterized 
by its intended impact on the minerals industries; 
for example, through the development of a techno- 
logic basis for new or revised standards and of new 
mining technologies or systems. However, close 
examination shows that no such difference exists in 
practice between the development of standards and 
the development of new technology. Research that 
develops a technological basis for new standards 
must, of necessity, provide a means for compliance. 
The inseparable and integral nature of research 
performed in response to both requirements is 
reflected in the structure of the Bureau programs. 
They are so designed that the concurrent develop- 
ment of a technologic basis for standards and an 
acceptable means of compliance must effectively 
address the legislative intent of Congress concern- 
ing mine health and safety research. 

The Bureau and its Health and Safety Program is 
directed toward the development and assessment of 
technology; technology has been defined as not a 
product but the ability to produce a product or the 
capacity to design. Since the Bureau is not in the 
business of producing devices for commercial use, 
our technology must be transferred to others who 
configure and market the product; hence the need 
for an effective Technology Transfer Program, as 
discussed below. 



PROGRAM INTERACTION 

Within the Health and Safety Program, allocation of 
funds has been 80 percent for coal mining and 
processing and 20 percent for metal /nonmetal mining 
and processing. While this may at first glance 
seem like a disproportionate distribution of re- 
sources, there is a considerable amount of inter- 
action, synergism, and subprogram leverage. A 
review of the fiscal year 1980 budget shows that 
approximately 65 percent of the total budget had 
impact on both coal and metal /nonmetal mining. 
While generally the metal /nonmetal subprogram 
benefits from the "front -end" studies conducted in 
the coal subprogram, there are instances of reverse 
infusions such as shaft fire protection research. 

TECHNOLOGY TRANSFER 

The utility of the Bureau's Minerals Research 
Program is measured in part by the degree to which 
technological advances are translated into practi- 
cal applications. Moreover, it is critically 
important that Bureau health and safety research 
be coordinated with related activities in the 
Federal and private sector. As a consequence. 
Technology Transfer is viewed as a vital and 
culminating element of the overall research and 
development process. Such transfer techniques as 
special publications, films, seminars, demonstra- 
tions, cost-sharing research agreements, and liai- 
son with mining, labor, manufacturing, and market- 
ing groups are employed to inform the mining commu- 
nity of research achievements. Both Bureau-spon- 
sored development and advances from such other 



activities as foreign research and development and 
independent research by the mining industry are 
reported. Since mining health and safety concerns 
the Bureau, MSHA, and other members of the mining 
community, it is best served by a continuous and 
lively communication among the concerned parties. 

Besides disseminating information on recent techno- 
logical advances, a primary objective of Technology 
Transfer is to maintain a forum for that communica- 
tion. Direct discussions of needs and problems at 
Technology Transfer activities have helped to 
establish a proper focus and balance for the Bu- 
reau's overall research and development program and 
are essential for identifying thrusts that will be 
required in the future. Seminars, briefings, and 
exhibits are three techniques used extensively to 
keep people abreast of Bureau research programs. 
Since 1978, 20 seminars, 12 briefings, and 15 major 
exhibits pertaining to minerals health and safety 
have been provided. 

While all of the preceding are necessary for the 
successful implementation of Technology Transfer, 
perhaps the most important and most effective is 
the in-mine demonstration. This is accomplished 
mainly in a section of a cooperating mine or in an 
independent "demonstration mine". Many of the 
Memorandums of Agreement discussed above are in 
fact for the purpose of in-mine demonstrations. 

Technology Transfer is viewed as an integral part 
of all research activities, beginning with the 
individual project's inception and continuing until 
results are successfully introduced into industrial 



use. Active review of projects from a technology 
transfer point of view is made toward Bureau re- 
search that helps to insure that the research 
activities are meeting real needs. 

PROGRAM EFFECTIVENESS 

The ultimate measure of success of Bureau research 
is the impact of a given program on the methods, 
products, and regulations affecting mining. Review 
of Sections II, III, and IV shows that much of the 
work can be categorized as applied research or 
applications engineering, which is typically of 
shorter range in terms of the time from accomplish- 
ment to implementation. Many of the projects in 
support of MSHA requirements are in this category. 
Although it is difficult to provide a characteriza- 
tion of typical times for a new product or process 
to have significant impact, a review of the litera- 
ture provides some insight as to normal experi- 
ences. The average development time of a new 
product in 1977 was 37 months ( Industrial Research . 
October 1977); studies have found that it takes 7 
to 10 years to put a new process or tool into 
widespread use ( Industrial Research . August 1974). 
Battel le reports that its limited sample of suc- 
cessful innovations covered widely varying time 
periods of between 6 to 32 years for the 10 innova- 
tions studied; the average time for implementation 
of the innovations was 19 years (The Role of Tech- 
nology Transfer in Innovation, Research Management , 
November 1974). 

The Bureau's Health and Safety Technology Program 
has been recognized by receiving IR'IOO awards in 



1978, 1979, and 1980. These awards, confirmed by 
Industrial Research Magazine, recognize each year 
the 100 top innovations introduced into the market- 
place. In 1978, the Bureau's awards were for the 
Parachute Stopping (p 27 ) and the Fibrous Aerosol 
Monitor (FAM) (p 16). In 1979 the award was for 
the Trapped Miner Location System (p 129), and in 
1980, awards were made for the NOx Dosimeter 
(Passive Personal Nitrogen Oxide Sampler) (p 34), 
the Combined Long/Short Duration Self-Rescue 
Breathing Apparatus, illustrated, (p 127), and the 
Inorganic Grouted Roof Bolt (p 57). 




While the Minerals Health and Safety Technology 
Program is just 10 years old, notable progress has 
been made to some degree in all research areas. 
The most frequent type of accomplishment falls into 
the categories of (1) development of data or tech- 
niques as a justification for new standards and/or 
modification of a standard and (2) development or 
adaptation of devices and systems to assist in 
compliance with existing standards. 

It should be noted that emphasis is beginning to 
shift from the development of retrofit technology 
to the design of new techniques and approaches to 
solve existing and anticipated problems. Retrofit 
technology has been useful and timely to assist in 
compliance, but there exist many difficult problems 
where retrofits are not feasible, and as more 
difficult mining conditions are encountered (as 
they are daily), even greater challenges lie ahead. 
An example is the case of the load-haul -dump (LHD) 
machine noise control, where retrofit techniques 
reduced noise from 100 dbA to 93 dbA. As a result 
of this noise reduction, the allowable operating 
time of a treated LHD machine for an 8-hour shift 
is increased by a factor of 2.5 over that of an 
untreated machine. It should be noted that the 
majority of the accomplishments relate to under- 
ground mining. Most of the Health and Safety 
Program addresses underground operations because of 
the greater complexities and the magnitude of their 
problems. 



FUTURE NEEDS 



The Minerals Health 
faces two important 



and Safety Technology Program 
challenges: (1) to meet the 



Congressional intent of the 1969 and 1977 Acts to 
reduce the risk of health and safety impairment in 
the mining industry as it is constituted today, and 
(2) to minimize the social cost of the now antici- 
pated increase in domestic minerals output--with 
particular emphasis on coal for domestic energy 
needs and for export. While there is some vari- 
ability in the estimates of annual coal demand by 
the year 2000, there is consensus that the require- 
ment will be of the order of 1 to 1 .2 billion tons- 
double that of the 1979 production. Hence, if 
there is not a lowering of the frequency of acci- 
dents, fatalities, and health impairments, twice as 
many miners will be adversely affected in the year 
2000 as today. The above estimates do not include 
a significant synthetic fuel industry, which is 
currently receiving universal support both in 
governmental and commercial circles. Additionally, 
the DOE is predicting by 1990 that U.S. coal ex- 
ports will increase from 5 million tons per year in 
1977 to 80-100 million tons. This alone accounts 
for a 15-percent increase in production. It is 
apparent that by the turn of the century, U.S. 
production will nominally double. Some of the 
increase will come from the thick Western deposits, 
with their unique health and safety problems, and 
some of the increase will come from the deeper, 
more difficult to mine underground deposits. In 
either case considerable work remains to be done. 

CONCLUDING REMARKS 

The Bureau's Minerals Health and Safety Technology 
Program is reaching a degree of maturity; that is, 
for present production methods, numerous techniques 



and procedures are in use or approaching the point 
where industry use is apparent. New mining condi- 
tions and methods continue to dictate the need for 
alternative health and safety methods. The innova- 
tions described in this report indicate the success 
of the Bureau's Health and Safety Research and 
Development Program in meeting the needs of those 
engaged in the minerals industries. Although we 
cannot quantify directly the role of research in 
such factors as decreasing mortality rates, statis- 
tics show that these rates have declined. Quanti- 
fiable indicators are the number of standards 
promulgated using research results as a basis, 
improvements in compliance, technical innovations 
as measured by the number of patent applications, 
technical publications, and the response to the 
technology transfer activities--briefings, reviews, 
and films. A most important indication is the 
growing involvement in Bureau programs through such 
avenues as Memorandums of Agreement, cost-sharing 
contracts, and the providing of sites for experi- 
mentation and demonstration. 

The status of the program, as reflected by these 
indications, is discussed in this report describing 
the Bureau's Minerals Health and Safety Technology 
Program. Sections II-IV detail some Program High- 
lights and Section V provides a summary of current 
and anticipated (within 2 years) accomplishments in 
each research area. In the following sections 
where prices are quoted, the figures were correct 
as of early 1981. Future results will undoubtedly 
show a continuing improvement of health and safety 
conditions encountered by the American miner. 



ALTH 



Respirable Dust. . . 



Noise 



Ventilation 



Industrial Hygiene 
Radiation 



.1: 



/ »4. 



'■ 'V '' 



Y *i 



^* •' 



iAMM 



w^ 






;.">^* 



ipirable Dust 



>^jt 



m % 



^ 



\ 




Idjor Problem Areas 

t Cutting at the face 

• Crushing and screening 
i^oof bolting an^ 

'^'drilling "* 

• Bagging e^.^-._, 

• Material transport 

• Dust measurement 



Appri 



(fV 



• Instrumentation 



dust control 




The Bureau's RESPIRABLE DUST CONTROL PROGRAM is 
directed at reducing hazardous respirable dust 
exposure in underground operations, in surface 
mining operations, and in preparation plants. 
Program emphasis is directed at controlling dust at 
the source, improved ventilation techniques to 
remove dust from the operator's area, improved 
control devices such as scrubbers, and personal 
protective devices such as canopy air curtains and 
cabs, or enclosures for surface mining operations. 
Additionally, work is conducted on the development 
of instrumentation for the monitoring of dust 
exposure. The program does not include epidemio- 
logical studies relative to respirable dust; such 
studies d.T^ the responsibility of NIOSH, with whom 
the Bureau coordinates closely. 

While ventilation traditionally has been the most 
effective control measure for respirable dust, some 
significant improvements in other techniques have 
been made in recent years, mostly relative to 
mining machines. An example of this is the Bu- 
reau's "shearer clearer" water spray system, which 
has reduced respirable dust exposure approximately 
50 percent in preliminary in-mine tests. 

Personal protective devices have been successfully 
utilized in some underground machine applications, 
and the use of cabs has been demonstrated to be 
effective not only for reducing dust exposure in 
surface mining operations but for noise control as 
well. Many innovative dust control techniques 
have been developed for the mining and process 
milling industry. As a result of Bureau research, 
process milling bagging machinery has been retro- 
fitted with an improved dust capture system. 



NONCLOGGING WATER SYSTEM : Machine-mounted water sprays are used 
to control dust generated at the coal face, but clogging of the 
spray nozzles creates problems. An improved system has been de- 
veloped for trapping coal and pipe scale particles that cause 
clogging. The system consists of a Y-shaped strainer, which 
screens out particles larger than 1/8-inch diameter from the 
dirty water; a hydrocyclone, which removes essentially all the 
remaining particulate matter; and a final filter. The Y-strainer 
and hydrocyclone are easily cleaned by opening two valves for a 
few seconds at the start of the shift. In field tests, the new 
system essentially eliminated clogging of the spray nozzles. The 
nonclogging water system is commercially available at an installed 
cost of about $800. Some 160 units have now been purchased by 
coal operators. 





IMPROVED SPRAYS - RIPPER : Based on laboratory studies, the Bureau 
developed engineering guidelines for positioning water spray 
nozzles on continuous mining machines and for selecting the 
nozzle type most effective in reducing respirable dust at the 
coal face. These guidelines have been used in installing water 
spray systems on a ripper-type continuous miner. The Bureau 
conducted a field testing program in the Pittsburgh coal seam to 
investigate the effect of water sprays in the suppression of 
respirable dust being formed while cutting. Results to date, 
using various nozzle locations and types, indicate that water 
sprays mounted in the conventional way on the top or side of the 
cutting boom are not particularly effective in reducing respirable 
dust, whereas water sprays mounted under the boom reduce respir- 
able dust by 30 to 50 percent. 



10 



WET AUGERS : The wet-auger system developed under a Bureau con- 
tract provides a simple, reliable, and effective dust control 
technique in which rotary water seals enable a water distribution 
system to bring water to nozzles located along the auger shafts. 
Machines can readily be retrofitted at a cost of $3,000 to $7,000 
each. The procedure not only reduces dust at the face by about 
50 percent, compared with use of conventional sprays, but also 
wets the coal more uniformly, thus reducing dust problems during 
belt transport. The wet auger has been standard equipment on all 
Wilcox continuous miners manufactured since 1974, and all other 
Wilcox continuous miners in the field have been retrofitted with 
wet-auger conversion kits sold by Fairchild Company or built by 
mining companies themselves. The number of Jeffrey lOOL miners 
in operation has decreased over the past few years, but of those 
remaining, most have been retrofitted with wet augers by using a 
conversion kit sold by Jeffrey Mining Machine Co., or have been 
equipped with wet augers. 








PRIMARY REDUCTION OF GENERATED DUST : The development of highly 
mechanized continuous mining machines in U.S. coal mines improved 
productivity, but the health hazard to the miners was increased 
because of the large amounts of respirable dust generated during 
the cutting process. To combat this problem, the Bureau of Mines 
is advocating the use of deep rotary cutting, which research has 
shown to be effective in reducing dust generation. Concurrently, 
the Bureau is investigating several innovative cutting concepts 
that show promise of reducing dust even further. One of these is 
the eccentric-head miner. Several companies have indicated an 
interest in obtaining licensing to produce the eccentric-head 
miner. This design is intended to produce a deep, linear cut with 
all bits at a constant, optimum depth. This would eliminate the 
shallow entry and exit portions that contribute to the dust pro- 
duced and energy consumed by a rotary head machine. It will 
attain high production at relatively low cutting speeds, elimi- 
nate dust entrainment by high-speed fanning action, and reduce 
methane ignition due to bit impact. 



11 



SECONDA RY 
double 



VENTILATION - DOUBLE 



DRUM SHEARER : An Eickhoff 340L 
ai^um Tongwall shearer has been retrofitted with a dust 
collector that utilizes a secondary exhaust ventilation system. 
The bottom of the undercarriage frame is enclosed to form an 
airflow duct, and air intakes are provided along the undercarriage 
and behind each cutting drum. The dust collector, installed at 
the tailgate end, consists of water sprays, a minicyclone panel, 
and a 5,000-cubic-foot-per-minute (cfm) exhaust fan. Cost of 
retrofitting is about $15,000. In underground tests at Eastern 
Associated Coal's Keystone No. 1 Mine, the secondary exhaust 
ventilation system reduced respirable dust by 60+ percent along 
the face, in close agreement with values obtained in laboratory- 
scale experiments. Work is continuing in this area to develop 
higher volume systems that will yield even greater dust reduc- 
tions. 




Air flow path 

Water spray i^f^ 




Operator 



DUST REDUCTION AT LONGWALL SHEARERS : Laboratory and underground 
tests have been conducted on a promising new water spray system 
for longwall shearers. Called the "shearer clearer", this system 
achieves improved effectiveness by using water sprays to generate 
air currents that act to hold the dust against the face and away 
from the shearer operators. In addition, these same sprays retain 
their conventional dust suppression function. In laboratory 
testing using tracer gas, the "shearer clearer" was more than 90 
percent effective. Underground testing is still underway, but 
preliminary data indicate at least a 50 percent dust reduction for 
the_ shearer operators. The big advantage of this system is that 
it is simple to install and maintain. If the results from contin- 
ued testing are favorable, it will represent a major breakthrough 
for longwall dust control. The accompanying photograph indicates 
how the "shearer clearer" sprays at the head end of a longwall 
shear act to move the dust from the region adjacent the drum to 
the face and away from the operator. 



12 



SECONDARY VENTILATION HOODS FOR FLUIDIZED BAGGERS : To alleviate 
a major dust source during the bagging of milled material, the 
Bureau has developed an exhaust ventilation system that captures 
airborne dust released from the bag during filling. Each nozzle 
of the bagger is fitted with a ventilation hood of sheet metal 
that surrounds two-thirds of the bag. Air velocity is maintained 
above 200 feet per minute, the air entrains the released dust and 
exhausts it through two rear ports where it is ducted to a dust 
collector. This procedure reduces by more than 85 percent the 
amount of airborne respirable dust that escapes. Tracer gas 
studies using sulfur hexafluoride (SF5) have shown that the hoods 
must be well sealed and balanced with room intake air systems, to 
be 100-percent effective. A secondary ventilation system of this 
type has been installed at Martin Marietta's whole grain silica 
plant in Portage, Wis., where it has helped to reduce dust concen- 
trations below compliance levels (0.10 milligram per cubic meter). 
Over 150 inquiries for information have been received. 





NOZZLE CLEANOUT SYSTEM : Spillage of material from the nozzle of 
the bagger and the throat of the bag as the bag is removed from 
the nozzle is a major source of dust around bagging machinery. 
To reduce such spillage, the Bureau has modified the bagger 
control circuit to delay the release of the bag and send a pulse 
of clean air through the nozzle. This modification typically 
reduces the amount of whole grain material spilled per bag from 2 
cups to 1 teaspoon. This represents a 95 weight-percent decrease 
in spillage, thus reducing considerably both the respirable dust 
hazard and the cleanup operations. Improved versions of this 
system are being developed under contract to deal with spillage 
problems of mineral flour materials. The system is now being used 
at a Martin Marietta Co. whole grain industrial sand plant. 



13 



TWIN SCRUBBER FOR CONTINUOUS MINERS : The Bureau of Mines and 
Jeffrey Mining Machinery, Inc. have developed a new type of scrub- 
ber and ventilation system that is built into the auger support 
frame (boom) of a Jeffrey 120L continuous mining machine. The 
twin scrubbers, one mounted into each side of the boom, contains a 
2,500-cfm fan, flooded fibrous bed scrubber panel, and a water 
droplet eliminator, and adds only a few inches to machine height. 
Rotation of the scrubber exhaust duct allows flexibility with 
various airflow arrangements to suit both blowing and exhaust face 
ventilation systems, and brattice distances ranging up to 20 feet. 
In full-scale tests at the MSHA surface facility at Bruceton, Pa., 
the twin scrubber-ventilation system showed striking improvements 
in face methane dilution when compared with conventional systems. 
Tests with a similar system at a coal mine in eastern Kentucky 
showed 90-percent respirable dust reduction and good acceptance by 
workers. Several twin scrubbers have been installed underground 
on blowing ventilation systems, and about 22 units are on order. 




LEGEND 




^^ Intake air 




^^^"^^ Dischorge air 




_^^^^^Water sprays 




^^J^ 


^i£^ ,"^^=^ -bcruDDer 




WETTED FIBER BED : A ^t^v^j small dust collector, developed under a 
Bureau contract, has achieved the highest efficiency for collect- 
ing respirable dust during Bureau tests. The scrubber illustrated 
consists of a 6-horsepower vaneaxial fan, a 0.25-inch-thick bed of 
0.0035-inch-diameter stainless steel wire, water sprays, duct 
transition, and a high-velocity, blade type water droplet elimina- 
tor (not shown in figure). This collector is nominally 4 feet 
long with a 16- by 16-inch cross section. Cost is approximately 
$5,000. In the laboratory, the system has a respirable dust 
collection efficiency of 95 percent, and the effluent is essen- 
tially free of water drops. From results of underground tests the 
Peabody Coal Co. reports that this type of scrubber has effective- 
ly controlled dust on a working section with blowing ventilation. 
To date, approximately 90 wetted fiber bed scrubbers have been 
ordered and/or installed on mining machines. 



14 



CANOPY AIR CURTAIN - UNDERGROUND FACE EQUIPMENT : The canopy air 
curtain developed under a Bureau contract for the protection of 
the continuous miner operator in coal mines has also found accept- 
ance as a personal protective device in metal /nonmetal mines. In 
this system, a centrifugal blower draws mine air through a filter 
that removes dust. The cleansed air is pushed through a flexible 
hose to a manifold mounted on the canopy above the operator and 
leaves the manifold through a perforated plate to flow down around 
the operator's head and shoulders. Installed cost varies somewhat 
with the type of machine; on a continuous mining machine it is 
about $1,500. The effectiveness of the system depends upon how 
often the operator has to move out from under the canopy, but in 
some cases personal exposure to respirable dust has been reduced 
by 75 percent. Currently, about 65 canopy air curtain systems 
have been installed in mines. 




UJ 

o 

z 
< 
m 
q: 
o 
w 
m 
< 




500 mg 



00 mg 



WAVE NUMBER 



ON-FILTER ALPHA QUARTZ ANALYSIS : A simple, fast, semiautomatic 
infrared technique has been developed under a Bureau contract to 
determine the amount of alpha quartz on a field respirable dust 
filter. A feasibility model indicated the concept was a powerful 
technique for analyzing the quartz in respirable dust samples. A 
model subsequently developed by the Bureau uses a desktop calcula- 
tor to drive the infrared spectrophotometer and collect the data; 
the calculator provides a direct output of the mass of alpha 
quartz present in the sample. Infrared collection filter analysis 
is accurate to within ±20 micrograms, and requires about 5 minutes 
of unskilled operator time. These results agree well with those 
obtained by an established X-ray analytical procedure using rede- 
posited samples. The Bureau is currently developing a rapid X-ray 
device for silica analysis, designed to measure quartz on a field 
collection filter, which shows promise. 



15 



PORTABLE LIGHT-SCATTERING RESPIRABLE DUST MONITOR : A portable, 
light-scattering resirable dust monitor, developed by the Bureau, 
provides a real-time reading of airborne dust levels directly in 
milligrams per cubic meter (mg/m^) of air. As with most light- 
scattering devices, the monitor should be calibrated specifically 
for each type of dust. State-of-the-art electronics and a clean 
air protective sheath over the optics assure repeatable measure- 
ments and virtually no zero drift. Three range scales (0-2, 0-20, 
0-200 mg/m^) can be used in varying ambient dust conditions. 
Concentration measurements as low as 10 
can be made. In addition to being 
evaluation of dust control methods and 
sources, the monitor is a candidate for use as a mining machine- 
mounted respirable dust monitor. The monitor is commercially 
available from GCA Corp. as the RAM-1 for $4,990. Approximately 
150 units have been sold by GCA Corp. 



micrograms per cubic meter 

extremely useful in field 

in locating airborne dust 





FIBROUS AEROSOL MONITOR (FAM) : Developed through joint NIOSH/EPA/ 
Bureau contract funding, the FAM is the first instrument of its 
kind that can detect, instantaneously , the fibrous aerosol concen- 
tration; that is, dispersed dust particles in the atmosphere. Two 
identical Fibrous Aerosol Monitors, developed and tested in the 
laboratory, showed that the FAM response is linearly correlated to 
the NIOSH-approved optical membrane filter count technique. FAM 
concentration readings are generally well within +25 percent of 
the optical membrane filter count determined from the FAM/optical 
count correlation plot. The FAM will respond to particulates that 
have sufficient shape irregularities to possess fiber characteris- 
tics such as the 3:1 length-to-diameter aspect ratio. The port- 
able FAM, shown in the adjacent photo is available from GCA Corp. 
for $9,990. The FAM was recognized as one of the top 100 innova- 
tions in 1978 and received an IR'IOO Award for its uniqueness. 
About 94 of these monitors are in use today. 



16 



Noise 



The Bureau's NOISE CONTROL PROGRAM, recognizing 
that compliance with curent noise standards is a 
difficult problem, has approached the problem 
through research on noise abatement, personal 
protective devices, and instrumentation to measure 
noise exposure in work areas. Principal emphasis 
has been to reduce noise at the source, as opposed 
to personal protection. Initial emphasis was on 
the development of retrofit control techniques; 
however, in some cases it has been necessary to 
develop noise control via new machine or plant 
design. As an example, retrofit of the noise 
control of pneumatic drills produced reductions 
from 115- to 118-dbA down to 104- to 106-dbA; 
however, for many drilling applications it was 
necessary to develop a new, inherently quieter 
drill that produces noise levels in the 92- to 95- 
dbA range. 






Major PdbblemAreas 

• Pneumatic drills 

• TransDort vehicles 



ApprA^bhes * 

• Noise abateftient 

• Personal protection 



exposurey 



Noise control techniques have been developed for 
diesel -powered equipment for both underground and 
surface applications; in the former, commercial 
noise control packages for load-haul -dump vehicles 
are being developed under cost-sharing contracts 
with industry. Because these treatments can be 
adapted by any surface mine using commercially 
available materials, they have been demonstrated at 
approximately 50 Bureau-sponsored workshops around 
the country. Noise control in preparation and 
beneficiation plants has proceeded with notable 
success. For example, a coal preparation plant was 
retrofitted to provide full -shift compliance. 
Through a cooperative program with the American 
Iron Ore Association, the Bureau is demonstrating 
noise control techniques for taconite plants, which 
are applicable to most noncoal processing plants. 



17 



LOAD-HAUL-DUMP VEHICLE : A survey of underground metal and non- 
metal mines, conducted under a Bureau contract showed that approx- 
imately 14,000 mine workers are exposed to noise levels in excess 
of 90 dbA, produced by an estimated 4,000 diesel -powered machines. 
Load-haul -dump (LHD) equipment was identified as the most serious 
noise hazard, with typical operator levels of 100 dbA. Two dif- 
ferent approaches to noise controlling LHD equipment have been 
taken; that is, both by retrofit of the old equipment and by 
redesign of the new equipment. A Wagner ST5A Scooptram was retro- 
fitted with noise control equipment resulting in an operator noise 
level reduction of about 7 dbA that increased allowable operating 
time by a factor of 2-1/2. In terms of machine design. Bureau- 
developed noise controls are being factory integrated into the 
design of EIMCO diesel -powered LHD's, Models 912 and 918. 





DISPATCH VEHICLE-DIESEL POWERED : The initial survey of under- 
ground diesel -powered equipment showed service vehicles to be the 
most prevalent noise source and the one affecting the largest 
number of miners, with an estimated 1,800 service vehicles and an 
average sound level at the operator of 94 dbA. A Getman dispatch 
vehicle was chosen by the Bureau to demonstrate that small diesel - 
powered vehicles could be quieted with a low-cost retrofit pack- 
age. The essential component of the quieting package is a partial 
enclosure around the air-cooled engine, located next to the 
operator station. This package, in conjunction with a silencer 
on the air intake and addition of sound-absorptive material on 
the underside of the operator canopy, reduced the noise level 
from 101- to 87-dbA. The quieted vehicle has performed satisfac- 
torily in a mine of the International Salt Co. 



18 



NOISE CONT ROL 
generated 



OF LONGWALL MINING SYSTEMS : A survey of the noise 
Tn domestic longwall coal mining operations has been 
completed and the machinery that contributes substantially to 
worker noise exposure was identified. Measurements made in five 
U.S. longwall mines suggest that longwall shearing machines con- 
stitute the most severe noise control problem in the face area, 
with typical noise levels at the shearer operator's position of 
93- dbA to 103-dbA. Longwall plows and in-web shearers produced 
less noise at the operator's position, while noise levels at the 
headgate operator's position were in excess of the 90-dbA level 
allowable for an 8-hour shift. Machinery that contributes to 
worker noise exposure in the headgate area includes the face 
conveyor drive motor and gearbox, stage loader and crusher, and, 
infrequently, the winning machine itself. This survey is being 
used to develop engineering noise controls that can be integrated 
into the design of future longwall mining systems. 





DIRECT AIRBORNE NOISE GENERATED DURING COAL CUTTING: 



Under 



Bureau contract, a laboratory investigation was conducted of the 
noise generated by the removal of coal from the face. Experiments 
were performed using a quiet, gravity-powered linear cutting 
apparatus. The purpose of these experiments was to establish the 
cause and effect relationship between coal fracture mechanisms 
and noise generation. This investigation has shown that the sound 
power of coal cutting noise sources is proportional to the mechan- 
ical power consumed during cutting. Thus, coal cutting noise can 
be reduced without reducing productivity by cutting coal with bits 
that have high cutting efficiency and use deeper depths of cut at 
slower cutting speeds than used in continuous mining machines. It 
should also be noted that slow, deep cutting has also been recom- 
mended to reduce the level of respirable dust at the face. 



19 



AUGER MINER RETROFIT: 



Approximately 400 auger miners are in 
Noise levels exceeding 106 dbA and oper- 



operation underground, 
ator noise dose exposures in the 300- to 500-percent range make 
this machine a major noise source. At current noise levels for 
the Jeffrey lOOL miner, allowable cutting time is approximately 
50 minutes per day, corresponding to about 50 tons of coal. A 
retrofit package developed in cooperation with Southern Appalach- 
ian Coal Co.'s Lens Creek Mine has reduced these levels from 106 
to between 99- and 100-dbA, which allows 105 minutes of cutting 
time and doubles production. The package shown here consists of a 
specially designed auger head with an isolated scroll and a 
system of damped cover panels on the top surface of the machine. 
In addition, the conveyor is equipped with isolating strips and 
bumpers. The installed cost of the package is under $4,000. 



^^^i«iite 



^^ 



■"':^^: 



''tl^L. 



mt: 




STOPER RETROFIT : One of the noise abatement techniques developed 
by the Bureau is designed for the pneumatic drills used in roof 
bolting. Sound levels emanating from pneumatic drills often 
exceed the allowable maximum of 115 dbA. A jacket muffler has 
been developed that provides over 10 dbA noise reduction, can be 
field-retrofitted to the drill, and weighs less than 10 pounds. 
The muffler can be fabricated without specialized equipment and 
installed by mine personnel. Material costs for the muffler are 
under $150, and a commercial retrofit kit is available from EAR 
Corp. The jacket muffler has been tested extensively on commer- 
cial drills in numerous coal mines and metal /nonmetal mines. 
Efforts are currently underway to develop a new class of stoper 
drill specifically designed for noise control. With new designs, 
stoper drill noise levels below 100 dbA are being achieved. 



20 



PNEUMATIC PERCUSSIVE DRILLS : The percussive rock drill is the 
most serious noise hazard in underground mines because it pro- 
duces noise levels on the order of 115 dbA at the operator's 
position. With retrofit noise control packages, noise reductions 
of more than 10 dbA have been achieved. The objective of this 
program is to develop a new stoper drill with noise control 
incorporated into its design. Based on previous experimental 
work carried out under Bureau contracts, six prototype production 
stoper drills are being designed and fabricated that achieve a 
noise design goal of 95 dbA at the operator's position with no 
decrease in drilling performance. This was accomplished through 
the use of a valveless cycle, an independent rotation motor, an 
integral muffler and a shroud tube for the drill steel. Produc- 
tive drilling times of up to 4 hours will be possible with this 
low-noise drill without exceeding Federal noise regulations. 





JUMBO PERCUSSIVE DRILLS : Jumbo-mounted percussive drills are used 
extensively in metal /nonmetal mines, where they pose a serious 
noise hazard to operators and bystanders. Typical noise levels of 
existing jumbo drills are 110- to 120-dbA. The Bureau has demon- 
strated that noise on a Gardner-Denver DH-123 jumbo-mounted drill 
can be reduced in excess of 16 dbA by covering the drifter with a 
noise-absorbing enclosure and using a drill -rod shroud tube. 
These demonstrations have shown that there is no reduction in 
drilling rates with the noise control treatments. This is an 
application of a concept originally designed under the project to 
develop a stoper described above. The system will be evaluated to 
arrive at a commercially acceptable product. Presently this noise 
controlled drill is undergoing extensive testing in an operating 
mine. 



21 



SILENCING THE FLAME CHANNELING PROCESS : One of the worst noise 
offenders in the quarrying industry is the channel burner, which 
uses a high-velocity flame jet to cut through heat spall able 
rocks and minerals, and generates operator noise levels of about 
125- to 130-dbA. Exposure to these noise levels is not permitted 
by noise regulations mandated by the Act of 1977. Under a Bureau 
contract, a quieter flame drilling system that matches the perfor- 
mance of the channel burner was developed. In a dimensional 
quarry where the benches are relatively flat, the flame drilling 
system with an integral muffler produces operator noise levels of 
about 100 dbA while drilling. The flame drilling system is opera- 
ted remotely and the cost per unit channel is about the same as 
that achieved by the conventional channel burner. The photograph 
shows the prototype flame drilling system in operation. The 
prototype is being field demonstrated to the industry. 





BULLDOZER NOISE CONTROL : A Bureau study of the noise exposure of 
miners in surface coal operations revealed that large track do- 
zers, especially older machines, represent the greatest single 
noise problem. Consequently, the Bureau sponsored a program to 
develop retrofit noise control treatments that can be readily 
fabricated and installed in the field by a mine operator. Three 
bulldozers, two Caterpillar D9G's, and one International TD-25C, 
were selected. The noise control treatments consisted of noise 
barriers, sound absorption, and vibration isolation, and in 
addition, each of the dozers either had, or was fitted with, a 
commercially available muffler. The noise reduction at high idle 
measured at the operator was 10- to 11 -dbA for the dozers without 
cabs and 8- to 11 -dbA for the dozer with cab (doors open and 
closed, respectively). The cost of materials ranged from approxi- 
mately $600 to $1,000. Installation for both dozers requires 
about 100 worker-hours. Long-term monitoring showed the system to 
be relatively durable and well received by the operators. 



22 



COAL 



PREPARATION 
shown that 



PLANTS : Surveys by MSHA and the Bureau have 
processing plants represent a significant noise ex- 
posure hazard to operators and maintenance personnel. Initial 
noise control technology developed by the Bureau for coal plants 
produced notable results. In particular, a 1974 study identified 
noise sources in coal plants and recommended solutions. To gen- 
erate reliable information on cost effectiveness of controls in an 
operating plant, and to demonstrate feasible engineering controls, 
a project was undertaken in conjunction with Consolidation Coal's 
Georgetown Preparation Plant. Through the use of resilient deck- 
ing for vibrating screens, leaded vinyl curtains around crushers, 
dryers, and screens, and strategically placed impact pads and 
strips on chutes, the plant, which had been cited on a noise 
violation, was brought into compliance. The project also gen- 
erated a significant volume of data and identified areas where 
more optimal control techniques are still needed. 





PROCESSING PLANTS : In extending noise abatement research to 
metal/ nonmetal processing facilities, initial efforts were direct- 
ed toward the high noise levels generally associated with the 
processing of taconite ore. Members of the American Iron Ore 
Assoc, are currently cooperating with the Bureau in a study to 
measure noise exposure and abate major noise sources, especially 
on secondary crushers. A survey of four taconite plants revealed 
that over 40 percent of the workers were exposed to more than the 
allowable 90 dbA. Noise abatement of secondary crushers is being 
explored at the Jackson County Iron Mine where an acoustical 
enclosure design has been selected for demonstration. Specifi- 
cally, an acoustical enclosure was built around a 7-foot, standard 



acoustical 

head, extra-heavy-duty Symons cone crusher. After the enclosure 
was installed, noise levels near the treated areas are about 90 
dbA. The enclosure has been deployed for 6 months, with no main- 
tenance problems. 



23 



NOISE ABATEMENT OF VIBRATING SCREENS : Noise from vibrating screens 
is generated both from the material being processed and from the 
screen itself. Nonmetallic decks had been shown previously to 
reduce material noise. The noise reduction and change in screen- 
ing performance was quantified for six nonmetallic decks using 
dolomite, granite, and coal. The nonmetallic decks were from 2- 
to 7-dbA quieter and from +1 to +10 percent less efficient than a 
steel wire cloth deck of the same open area. Damping of the 
sidewalls and isolation of the drive mechanisms had been shown, in 
a development configuration, to reduce the noise of the screen 
itself. Four prototype damping treatments gave reductions up to 
4.9 dbA, and the mechanism isolators gave an additional 2.1 dbA. 
The treatments were successfully life-tested both in the labora- 
tory under simulated conditions and in the field on a commercial 
screen. 





PREDICTING THE SCREENING PERFORMANCE ON NONMETALLIC DECKS : 
Nonmetallic decks are increasingly used on vibrating screens 
because of their lower noise and increased life as compared to 
metal decks; however there is little information for predicting 
the screening performance of the nonmetallic deck. A Bureau 
contract is developing this information to aid equipment operators 
in selecting the proper deck for the application. To do this, a 
computer-based simulation model will be developed to predict the 
performance, and will include the following variables: zero or 
twenty-degree inclination, straight line or circular motion, deck 
hole size and shape, material hardness, and material size distri- 
bution. The empirical values of variables will be obtained from 
tests on screens with the deck surface narrowed to 1 foot. The 
tests will also be run on a full-size screen deck for verifica- 
tion, and then the model will be used to generate performance 
information for the screen user. 



24 



PERSONAL AUDIO DOSIMETERS : Because the measurement of noise can 
be difficult and hazardous in underground mines, MSHA has increas- 
ingly relied on the use of personal audio dosimeters to quantify 
noise exposure. Under a Bureau contract acoustical performance 
standards for such devices were specified by MSHA as a result of 
testing of audio dosimeters. Performance levels of an initial 
evaluation were published, providing a guide for manufacturers to 
improve their products; and MSHA has issued a list of audio dosi- 
meters whose performance is acceptable for underground mines. 
Responding to a need for a more thorough analysis of exposure, a 
Bureau in-house effort has developed a time-resolved audio dosi- 
meter, which details the time history of a noise exposure. Simi- 
lar noise measurement units are commercially available. Present 
Bureau research activities involve developing environmental test 
criteria for the survivability and reliability of personal audio 
dosimeters in hostile mining environments. 




25 



lation 




pi f New stoppings 

w .ace- ventTTarETbn^ Improved analysis 

• Heat in deep mi nes • New cooling systems 

^. • McH'imi-g^T^n noncoal-inines • Techniques to forecast 
. ■ *^-v...»—jiie thane emissions 

r**^ t Alternative air movers 



The primary objective of the VENTILATION RESEARCH 
PROGRAM is to develop more effective methods of 
maintaining sufficient fresh airflow in underground 
working areas to control respirable dust, reduce 
the air temperature in hot mines, dilute methane 
to safer levels, and remove other potential toxi- 
cants. Emphasis has centered on the development of 
ventilation control systems that can be mounted on 
face production equipment and of improved ventila- 
tion control devices such as stoppings, bulkheads, 
and cooling plants. Additionally, developmental 
work has been directed to in-mine air measuring 
techniques. Ventilation techniques are used exten- 
sively in the respirable dust program to reduce the 
respirable dust exposure of operators, and in the 
methane control program to mitigate the hazards of 
methane in underground mine workings. It should be 
noted that, while the ventilation techniques for 
methane control were funded under the Methane 
Control Program, they are discussed in this sub- 
section for the purpose of consolidation. 

Significant progress has been made in controlling 
airflow and in reducing air leakage by means of 
novel, but simple, stopping systems. These devices 
have been tested extensively in operating mines 
and now are commercially available. To date, 
several mines have used these devices on a produc- 
tion basis. 

Simple, but effective, cooling devices were devel- 
oped for use in deep mines. A direct-contact 
water-spray-to-air cooling device tested under- 
ground has shown twice the effectiveness of conven- 
tional fin tube coolers and is self-cleaning. 



26 



PARACHUTE STOPPINGS : A parachute-type stopping intended for both 
emergency and production use in hardrock mines has been developed 
by the Bureau of Mines. The parachute stopping can be installed 
by rescue crews in a matter of minutes to reestablish and reroute 
ventilation air as needed in an emergency to make temporary 
changes in the mine ventilation system. The parachute stopping 
is erected by attaching the cords to a fixed point and rolling it 
out downwind. The air moving in the mine passage lifts it and 
holds it in place, automatically effecting a seal. Parachute 
stoppings have been successfully tested in several metal /nonmetal 
mines, and are now commercially available. An IR»100 Award was 
made to the Bureau for this design in 1978. 





QUICK-FIX BLOWOUT STOPPING : Constructing and maintaining tempor- 
ary or permanent stoppings in hardrock mines is expensive in terms 
of both time and materials, especially where blast damage to 
stoppings is common. The Bureau of Mines has developed a new 
quick-fix blowout stopping that can be blown down by blast forces 
without incurring permanent damage. Compared with conventional 
brattice stoppings or wood bulkheads, the quick-fix blowout stop- 
ping is easier and faster to install, easier to maintain, and an 
efficient air barrier. The stoppings are attached to the mine 
walls, roof, and floor by means of short straps. One or more of 
these short straps may tear out under strong blast forces and 
allow the stopping to collapse, avoiding any blast damage. The 
stopping can be quickly reinstalled simply by replacing torn 
straps where necessary. Quick-fix blowout stoppings are in wide 
use in uranium mines, and are commercially available through two 
manufacturers. 



27 



DA MAGE-RE SISTANT BRATTICE: 
large 



Maintaining stoppings in airways with 

a large cross section is difficult, particularly where these 
stoppings are subjected to blast forces. The Bureau of Mines has 
developed a new damage-resistant brattice, that gives a good air 
seal and also resists damage from blasting. It consists of a 
series of adjacent vertical panels fastened to each other with 
Velcro strips sewn along the panel edges. The Velcro seals make 
the stopping a good air barrier, but the seals open under blast 
forces, avoiding permanent damage to the stopping. Damage-resis- 
tant brattice stoppings have proved successful in the White Pine 
Copper Mine, the Retsof Salt Mine, and the Grand Rapids Gypsum 
Mine. Damage-resistant brattice is now commercially available. 







BEFORE EXPLOSION 



* ' * -^■'. • ■ 



^-Vr? 



^^'^ ^ \ 



■^^ : .'If 




SELF-SEALING BRATTICE: 



The Bureau of Mines has developed a self- 
can replace stoppings blown down by an 



sealing brattice that 
explosion. The quickly installed stopping restores ventilation 
and prevents the accumulation of explosive or toxic gases. The 
self-sealing brattice is secured to the roof, ribs, and floor by 
anchoring its nylon edge strip at several points using extensible 
poles, spads, or available projections such as roof bolts. The 
air pressure in the entry pops open the chute of lightweight 
sailcloth, forcing it tightly against the floor, roof, and rib. 
Sealing is as good as or better than with a conventionally erected 
brattice stopping. Since the edge of the stopping lies flat 
against the rib or other surface, it tends to be self-sealing, 
enabling the stoppings to be installed quickly. The 4.5-pound 
self-sealing brattice can be rolled into a compact 6- by 15-inch 
package. 



28 



SPRAY "FAN" : The conventional water spray can serve as a simple 
"aM effective air mover. If all the water sprays on a mining 
machine are realined to take advantage of their air-moving abili- 
ties, the natural airflow pattern can be enhanced even more than 
with a diffuser fan. By placing a few nozzles on the intake side 
of the machine, as shown here, and tilting the front sprays 
slightly to one side, ventilation efficiencies of 75 to 85 percent 
can be achieved. Changing the brattice position from one side of 
the entry to the other can be accommodated by having two separate 
spray "fan" systems controlled by a crossover valve — one to move 
air from right to left, and the other to push it the opposite 
way. Several coal mining companies are now using spray "fans". 
At latest count, 300 continuous miners have been equipped with the 
system. Some companies have obtained MSHA approval for greater 
than 10-foot exhaust curtain setbacks by installing the spray "fan' 
system. 



.\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\- 





INDUCTION VENTILATION FANS : Induction ventilation fans are used 
in the large underground mines, particularly salt and limestone, 
to ventilate face areas. No tubing is attached to the fan; fresh 
air is carried forward with the high-velocity fan jet. This jet 
entrains additional air and may induce a considerable 
However, induction fan effectiveness has always been 
because of the fear that most of the induced air is 
contaminated and is simply being recirculated. Bureau 
tests with SF5 tracer gas have shown that these fans can 



airflow, 
doubtful 
already 
of Mines 
be sur- 
prisingly effective if properly located. These tests have provid- 
ed operators with general guidelines for the placement and use of 
ventilation fans. 



29 



ASSESSING METHANE BUILDUP HAZARDS FROM DUST SCRUBBER RECIRCULATION : 
Machine-mounted dust scrubbers reduce dust at coal mine working 
faces, but recirculate some of the air that passes through them. 
At MSHA request, possible buildup of methane due to this recircu- 
lation was investigated. Experiments conducted in a full-scale 
model of a working face area indicated that methane levels depend 
on the location of scrubber exhaust, but that scrubber recircula- 
tion does not substantially increase the methane concentration. A 
study of gas explosions attributed to recirculation showed that 
the high levels of methane were due to a lack of fresh air, rather 
than to recirculation. This indicates that dust scrubbers are not 
hazardous, that recirculation may be much more useful than previ- 
ously thought, and that it can be practiced safely if the fresh 
air supply is adequate. 





WATER SPRAY VENT TUBE COOLER : Working levels in many U.S. hard- 
rock mines continually descend to greater depths, and working 
locations move progressively farther from shafts, resulting in a 
deteriorating working environment due to increases in temperature 
and humidity. The Bureau has developed the water spray vent tube 
cooler for use in cooling these areas. The prototype version 
consists of a lO-foot section of 16-inch-diameter fiberglass 
ventilation tubing with six, evenly-spaced water sprays located 
inside. This section of rigid tubing is installed into a mine's 
flexible ventilation tubing line that conducts fresh air into a 
working stope. The cool water line from the mine is connected to 
the six water sprays, and the warm ventilation air being supplied 
to the stope passes through the sprays and is cooled by the direct 
contact with the cool water. Preliminary tests at the Homestake 
Gold Mine, showed that- the cooler supplied in excess of 6 tons of 
refrigeration to the ventilation air. Further refinement is 
continuing under a Bureau contract. 



30 



BRATTICE WINDOW METHOD FOR MEASURING LEAKAGE ACROSS MINE STOPPINGS : 
7^?i extensive series oT laboratory tests were conducted under 
Bureau contract to improve the brattice window method. The labor- 
atory tests defined the window coefficients and the accuracy of 
the method using different measuring techniques for a range of 
window sizes and shapes. The mine tests developed techniques for 
quickly erecting the Temporary Test Stopping (TTS) in a crosscut, 
making the measurements, taking down the TTS and moving it and the 
test equipment to the next crosscut. The time period for the 
total cycle ranged from 15- to 45-minutes, depending on the pro- 
perties of the crosscut surfaces. The total weight of the TTS and 
test equipment carried by the two miners conducting the tests was 
approximately 40 pounds. A modified form of the brattice window 
method was used by another Bureau contractor to successfully 
evaluate a variety of stoppings in several hardrock mines. 





SFfi TRACER GAS : 

complex. Many 

readily studied 

Bureau of Mines 

fluoride (SF5), 

empl oyed 

through 

adjacent 

from an 

various 

also been 

section and low 

underground cooling 



Mine ventilation systems are generally very 

aspects of a mine ventilation network cannot be 

by anemometer and smoke cloud techniques. The 

has successfully used a tracer gas, sulfur hexa- 

to analyze some of these problems. SF5 has been 

to measure recirculation of return air caused by leakage 

old stoped areas, to check potential leakage from an 

mine, to trace 10,000 cubic feet per minute of "lost" air 

intake airway, and to measure transit air time through 

uranium mines, including the Kerr-McGee mines. It has 

used to measure airflows in airways of large cross 

flow velocity, to evaluate recirculation caused by 

plants, and to evaluate the effectiveness of 



coal mine gob ventilation. 



31 



ACCURATELY MEASURING LOW AIR VELOCITIES : The Bureau of Mines 
conducted in-mine tests to determine correction factors applicable 
to low-velocity airflows (below 150-feet-per-minute) measured by 
the smoke cloud, vane anemometer, and oil of wintergreen tracer 
gas techniques. The average correction factors found for these 
methods of measurement were lower than those reported in the 
literature for use with higher velocity measurements. All tests 
measured airflows with controlled average velocities ranging from 
50- to 100-feet per minute. Correction factors averaged about 
0.75 for readings taken by the centerline smoke cloud method, 
remotely controlled and stick-held centerline anemometer, and 
split traverse stick-held anemometer. For hand-held centerline 
anemometer and oil of wintergreen tracer gas readings, correction 
factors averaged about 0.67. 





METHANE HAZARDS IN NONCOAL MINES; 



Injuries and fatalities from 



methane explosions in metal /nonmetal mines are not uncommon, and a 
major contributor to these accidents has been the failure to 
recognize that methane could accumulate in sufficient quantities 
to be hazardous. Consequently, the Bureau of Mines has conducted 
a study to determine whether trace methane measurements made in 
return airways of these mines might serve as a rough guideline as 
to the extent of the hazard. For this purpose methane measure- 
ments in the return of each mine were compared with that mine's 
gassy-nongassy classification. The study showed that those mines 
classified as gassy by MSHA generally had substantially higher 
methane concentrations in their return air than did those classi- 
fied as nongassy. Thus, return air measurements are a useful 
forecasting tool. 



32 



Industrial Hyg 











The Bureau's INDUSTRIAL HYGIENE PROGRAM is aimed at 
providing the information, analytical tools, and 
monitoring and warning devices necessary to assure 
that potentially toxic or dangerous gases are 
maintained at safe levels in underground mines and 
related surface installations. Particular emphasis 
has been placed on developing small, lightweight 
samplers or analytical instruments necessary to 
rapidly and routinely determine conditions in 
underground mines. One example is a dosimeter 
that can be worn by a miner during an 8-hour shift 
to accurately measure his exposure to toxic gases 
such as nitrogen dioxide (NO2). Additionally, 
handheld indicating carbon monoxide (CO), nitric 
oxide (NO), and methane (CH4) devices have been 
developed that give increased reliability, are 
direct-reading, and eliminate, or minimize, the 
need for stain tubes to assess in-mine conditions. 
Special studies are underway to control the quanti- 
ty of toxic gases emitted into the mine atmosphere. 
Related studies are focused on minimizing the toxic 
gases produced by explosives used underground. 



nhlern Area: 

:yas4s in under- 
v'fid mines 

* Blasting products 

* Diesel emissions 

* Equipment fi res 

* Chemical extingu,^"""' 
ment products 



Approaches .} . * 

• Improved explu>^ 

• Monitoring and^^ 
instrumentat| 

t Diesel emisst. 

tion and conti^ 

*-!#Determi nati onBF iSffferrnal 
iosi,|;-^nBroducts 






The effect of diesel emissions on underground mine 
air quality is being evaluated; significant pro- 
gress has been made on developing control tech- 
niques to reduce the potential hazards from diesel 
emissions. Through the use of a special filter, 
particulate emissions have been reduced by approxi- 
mately 80 percent. The exhaust emission character- 
istics and health advantages of alternative power 
sources, such as Stirling engines and metal-hy- 
dride-storage hydrogen engines, relative to conven- 
tional diesel power sources are being investigated. 



33 



SURVEY OF COAL MINE SURFACE AREAS : At the request of MSHA, the 
Bureau has conducted an industrial hygiene survey of 59 facili- 
ties composed of the shops, preparation plants, storage areas, 
etc., utilized both by underground and surface coal mines. 
During the program, a training course entitled, "Instructor's 
Teaching Guide, Surveying Inhalation Contaminants in Above Ground 
Coal Mining and Processing Work Areas," and book entitled, "Hand- 
book of Inhalation Contaminants in Above Ground Coal Mining and 
Processing Work Areas," were prepared. Both of these training 
materials are being used by MSHA in training courses at Beckley, 
W. Va. Guidelines for mine inspectors are provided for checking 
compliance with the Federal Mine Safety and Health Amendments Act 
of 1977, Public Law 95-164. 





PASSIVE PERSONAL NITROGEN OXIDE SAMPLERS : The passive NO2 gas 
sampler and analysis technique, developed under Bureau contract, 
will be commercially available from MDA Scientific, Inc. in kit 
form. The plastic sampler, worn clipped on the pocket or collar 
of the miner, can be assembled from parts in the kit. The sampler 
system is contained in two suitcase-size kits containing all 
necessary parts for exposure and analysis of 100 samplers. In 
addition to the determination of NO2, the concentration of total 
nitrogen oxides can be measured by adding a chromic-acid-treated 
disk to the sampler. Using the kit, analysis of miner exposure to 
both NO and NO2 can be determined immediately at the mine site 
without sending samplers to a remote laboratory. An IR'IOO Award 
was granted for this sampler in 1980. 



34 



HANDHELD DIRECT 
bel t-worn 



READING 
direct reading 
measure toxic gases 



CO , NO, AND N O 
detectors. 



DETECTORS : Handheld or 
eveloped under Bureau con- 
and NO2 in the mining 



tract, measure toxic gases such as CO, NO, 
environment. The detectors, 6- by 4- by 2.3-inches and 1.5 pounds, 
can measure toxic gases formed from fire, explosions, or diesel 
engine exhaust; they replace the stain tubes currently used by 
MSHA and the mining industry. Each detector has an alarm, which 
gives audible and visual indication of high gas concentration, and 
a dosimeter (when used in conjunction with a support console), 
which will indicate gas exposure in ppm-hours and can be used to 
calculate time-weighted-average gas concentration levels. A 
recorder output jack in each detector may be used to obtain a 
permanent record of measured gas concentrations and aid in statis- 
tical analysis of gas concentration fluctuation. The CO detector 
is currently available from the General Electric Co. The NO 
detector will be available in approximately a year. 





EVALUATION METHODS FOR GAS DETECTION DEVICES : In response to the 
need for uniform operational methods for the evaluation of gas 
detection devices, (ranging from throwaway badges and detector 
tubes to machine-mounted or fixed location monitors), the Bureau 
has completed a manual entitled, "Procedures for the Test and 
Evaluation of Gas Detecting and Indicating Devices." This docu- 
ment can be used in conjunction with the operating features of the 
device to be evaluated in order to define the set of tests that 
completely characterize the device's performance. Evaluations 
were conducted with area monitors for NO and NO2 gases and with a 
combination oxygen deficiency, combustible gas, and carbon monox- 
ide alarm. An oxygen sensor that uses a capillary diffusion path 
for transport has been tested and found to have a pressure effect 
one- tenth that of other oxygen sensors. These evaluations serve 
to alert consumers and manufacturers of the devices of the instru- 
ments' characteristics and problem areas. 



35 



TOXIC GASES FROM MATERIALS USED IN UNDERGROUND MINING : This study 
assessed the potential hazards associated with the thermal oxida- 
tive decomposition (as opposed to combustion) of organic materi- 
als used in underground mining such as conveyor belt materials, 
solvents, fire extinguishants and retardants, and hydraulic fluids. 
Samples were heated in a flowing air stream in a stagnation burner 
or in a sealed system, and the products resulting from this heat- 
ing were separated by trapping at various temperatures and ana- 
lyzed. The compositions tested included basic polymers, fibers, 
additives, flame retardants, plasticizers, preservatives, conveyor 
belt materials, solvents, fire extinguishants, hydraulic fluids, 
and woods. The degradation data obtained were reduced and tabula- 
ted to give potential toxic load values and toxicity contributions 
of the major decomposition products. Comparisons are made between 
toxic load values in quiescent and dynamic environments. This 
information serves as a guide for MSHA-approval of materials used 
underground. 






^ 


IN 


BH 




^ 1 


H 


i^l^^^^FV 




M 


m 


jIH 




m 


If 


IvJMHlj^^H 




U^j^ 




mI 



TOXIC GASES FROM EXPLOSIVES : Toxic gases produced by the detona- 
tion of six explosives were measured in an underground hardrock 
metal mine. The six explosives included two semigelatin dyna- 
mites, three slurry explosives and an ammonium nitrate, fuel-oil/ 
ammonia dynamite combination. Explosives were detonated at the 
face of a drift, and the toxic gases produced by the detonation 
were trapped at the end of the drift by a bulkhead located a short 
distance away from the face. The same explosives were fired in 
the laboratory in the instrumented, large (38,000-liter) chamber 
that was developed to replace the Bichel gage and Crawshaw-Jones 
(C-J) apparatus for schedule requirement testing for gases from 
explosives. The results showed that the large chamber is equiva- 
lent to the C-J apparatus in the measurement of carbon monoxide, 
but much better in the measurement of nitrogen oxides. Refinement 
of laboratory tests that reproduce field conditions continues. 



36 



CO? MONITOR FOR DIESELS OPERATED UNDERGROUND : The successful use 
of diesels in underground mines depends on their demonstrated 
capability to increase worker safety, health, and production, in 
relation to other power sources. In response to MSHA requests. 
Bureau-funded laboratory and field studies have shown: (1) level 
of one exhaust component (CO2) rises significantly faster than 
other more toxic exhaust components if a diesel engine is operated 
in a confined or poorly ventilated area; and (2) level of CO2 is a 
direct indicator of the efficiency of the ventilation to remove 



diesel exhaust, 
setable alarm and 
warn the operator 
reduced within 2 



Vehicle-mounted CO2 prototype monitors with 
direct CO2 indication have been developed that 
and shut off the engine if the CO2 level is not 
minutes. The vehicle-mounted monitors permit 



operator monitoring of ventilation effectiveness. 





AIR-QUALITY CONTROL FOR MINES USING DIESEL EQUIPMENT : Several 
projects are underway to study the mine atmosphere through instru- 
ment sampling, and to relate the various gaseous and particulate 
concentrations to mining activities, ventilation, and identifiable 
sources such as diesel exhaust, blasting fumes, and jumbo drills. 
Gaseous and particulate contaminants are being investigated and 
the relationship of diesel exhaust from moving vehicles to venti- 
lation in underground mines is being modeled. The results of this 
research will be used to prepare engineering guidelines for the 
development and operation of mines using diesel equipment. This 
Bureau research is already finding use by MSHA and the mining 
industry relative to the safe use of diesels underground. Diesel - 
mounted CO2 monitors are being demonstrated in underground mines. 
Strategies for air quality control and monitoring are being devel- 
oped that will specify the location and frequency of measurements, 
the types of devices, and the accuracy desired. 



37 



CONTROL OF DIESEL ENGINE EXHAUST : 

exhaust control 



A Bureau in-house project has 
filter for removal of particu- 



devlsed a dleseJ 

lates. The filter consists of a stainless steel holder containing 
a commercial filter material with a deep stainless steel/fiber- 
glass pad. The unit is mounted in line with the exhaust and is 
capable of removing 75- to 90-percent of particulates (95 percent 
of sulfates) over several shifts with moderate increase in engine 
backpressure. Combinations of this filter in tandem with catalytic 
converters and other control systems show promise for considerable 
lowering of concentrations of particulates, nitrogen oxides, and 
combustible components. 





MAINTENANCE FOR UNDERGROUND DIESEL ENGINES: 



Diesel engines can 



emit potentially harmful pollutants. Increases of these emissions 
can be attributed to inadequate maintenance and related design 
factors. Detailed knowledge on current use, design, and main- 
tenance of diesel -powered equipment in underground coal and metal/ 
nonmetal mines was gained through an extensive field assessment 
program. The program included visits to underground mines and 
engine rebuilding shops, and interviews with mine equipment manu- 
facturers and State and Federal enforcement agencies in the United 
States, Canada, United Kingdom, and West Germany. The study 
indicates that engine maintenance is a controlling factor in 
minimizing diesel pollutants and that a sustained maintenance 
program will increase engine life and equipment availability while 
reducing fuel and ventilation costs. Specific maintenance recom- 
mendations are being developed for the mining industry to aid in 
achieving these benefits. 



38 



'Radiation 



The Bureau's RADIATION RESEARCH PROGRAM 
seeks to develop the information, instru- 
mentation, and methods of control neces- 
sary to protect personnel from radon gas 
and its airborne radioactive daughters in 
underground mine work areas. Major empha- 
sis has been directed to the development of 
mineworthy personal dosimeters that accur- 
ately measure worker exposure to radiation. 
The devices are now being modified as a 
result of active mine testing. Two of the 
devices use a battery-powered air pump, and 
one device is passive. Three types of 
detectors are being evaluated. 



The Bureau also operates as a test facility 
an underground uranium mine, which provides 
typical mine environment conditions for 
radiation-related research projects. The 
facility is being used to evaluate various 
types of instrumentation for measuring 
radiation hazards. Studies are also under- 
way on air cleaning systems designed to 
remove radioactive particulates from mine 
atmospheres through the use of filter 
media. 



[Areas 

• Exiaaes^ exposure 

• Measurfln^nt of exposure 



Approaches 

• Sealants 

• Ventilation 

• Scrubbers 

• ^Lniprgved instrumentation 
t Selective backfilling , 



In a related area. Bureau research has 
demonstrated that the use of sealants 
applied to exposed rock surfaces in active 
uranium mines can reduce radon-gas escape 
into the ventilation system up to 75 per- 
cent. Ongoing performance monitoring of 
these sealants for the past seven years has 
shown no deterioration of the sealant- 
coated rocks. 



39 



RADON DAUGHTER DOSIMETER : Alpha particle irradiation of lung 
tissue, due to Inhalation of radon daughters, is the leading cause 
in the increased incidence of lung cancer among uranium miners. 
Thus, it becomes important to have reliable and accurate methods 
of measuring exposure to radon daughters. Tests by the Bureau and 
MSHA show that a personal radon-daughter dosimeter measures indi- 

more reliably than the current grab sampling 
Bureau has tested three types of radon-daughter 
include a passive nuclear track detector system, 
an active thermoluminescent detector system, and an active elec- 
tronic detector system. Design changes are being made in the air 
pumps of the latter two systems to increase reliability, and the 
thermoluminescent detector holder is being modified. Modifica- 
tions are also being made on the passive nuclear track dosimeter. 
Upon completion of these changes, this technology will be avail- 
able to MSHA and the uranium mining industry. 



vidual exposures 
techniques. The 
dosimeters; these 





CONTINUOUS WORKING LEVEL DETECTOR (CWLD) : A working level detec- 

radon daughter exposure has been 

consists of a beta detector 

continuously counts beta 

This information can be 

a scaler counter to 



tor for continuous measurement of 
developed by the Bureau. The unit 
(pancake type Geiger-Mueller tube) that 
activity collected on a filter paper, 
either recorded or measured directly with 



allow calculation of exposure in working level units. Since the 



beta detector also responds to gamma rays, 
subtracted from the total measured activity, 
of the working level measurement is about 10 
for which a patent was recently received. 
National Park Service to monitor exposure of 
caves. Currently, the Bureau is selecting 



that response must be 
The overall accuracy 

percent. This device, 
has been used by the 

its employees in park 
a contractor to build 



these detector units. This device will 
radiation alarm system under development. 



be incorporated in a 



40 



REMOTE WORKING LEVEL MONITOR (RWLM) : To improve the air-sampling 
techniques for radon daughter products, the Bureau developed an 
automated working-level monitor using remote detectors. This 
system, called a Remote Working Level Monitor, is a multichannel, 
totally automatic unit designed to measure working levels and 
individual radon daughter concentrations, RaA, RaB, and RaC, and 
to record these data. It is capable of taking up to 200 samples 
at the operator-selected time intervals. This system allows 24- 
hour monitoring without the need of operating personnel. Similar 
units have been used by the Environmental Protection Agency to 
measure radiation hazards in dwellings located over backfilled 
potash mines in Florida. A commercial version of the original 
design is available from Harshaw Instruments. 





URANIUM MINE BULKHEAD DESIGN; 



The radioactive contamination in 



uranium mines is attributed in part to leakage of radon gas from 
previously mined areas due to improperly sealed bulkheads. 
Methods for reducing this leakage are improved construction and 
sealing methods, and regulating pressure across the bulkhead. The 
most effective control of radon leakage is by installing a plastic 
pipe running from the bulkhead to a low-pressure exhaust area. 
The slight pressure differential (greater in front of the bulk- 
head) reduces leakage into the ventilation system by more than 
half, at negligible cost. The system has been successfully used 
for three years by the United Nuclear Corp. at the Churchrock Mine 
in Gallup, N. Mex., and the Exxon Corp. at the Buffalo Shaft Mine, 
Casper, Wyo. 



41 



RADON BARRIER COATINGS : Miners working in underground mines have 
a greater than normal incidence of lung cancer from breathing the 
radioactive decay products of radon gas that enters ventilation 
systems from the surrounding rock. Sealants applied to exposed 
rock surfaces can reduce radon entry into the ventilation system 
by 60 to 70 percent. The Bureau has tested such sealants in the 
laboratory, in experimental dormant mines, and in active mines to 
determine their potential for reducing miner exposure. Perfor- 
mance monitoring nearly five years after application of a water- 
base epoxy shows no deterioration. Ore samples coated with the 
same material have been stable for more than eight years. Evalua- 



tion of the effectiveness 
continue through 1981. 



of sealants in active uranium mines will 





CLASSIFIED MILL TAILINGS FOR BACKFILLING: 



By using classified 
the volume of air 



mill tailings for backfilling worked-out areas, 
needed to control radon and its decay products is reduced, ground 
control is improved, and the surface environmental problem is 
reduced. Bureau tests are determining whether classified mill 
tailings can be used for backfilling without increasing the radia- 
tion hazard to the underground miner. Two worked-out stopes have 
been monitored continuously while being backfilled. Preliminary 
results show increased radon concentration during the actual back- 
filling but a return to normal when the backfilling is stopped. 
Two additional stopes are being monitored to verify the observed 
increases in radon concentration. 



42 



RADON CONTROL MODELING : Mathematical models have been developed 
to resolve questions on diffusion and convective flow of radon 
through porous media. Some of the analyses are on radon flux 
(emanation) versus barometric pressure changes, the effect of ore 
body length on overpressurization, and radon loss through pin- 
holes in an otherwise impermeable barrier. Although there are 

with pressure cycling, the average radon 

cycle is the same for repeated cycles. 

an ore body without a pressure and radon 

benefit. Radon flux from the 6.75-meter 

value in about 1 hour and then returned 

in about 30 hours. For the 135-meter 

occurred in 10 hours and returned to 

Contrary to the literature, analyses 



large changes in flux 
discharge during each 
Overpressurization in 
sink has a transient 
model reached its lowest 
to the steady-state level 
model, the minimum flux 



steady-state in 800 hours, 
indicate that pinholes in a radon barrier are not extremely seri- 
ous; between 30 and 40 nickel -sized holes are necessary to cause a 
10-percent loss in barrier effectiveness. 




"v^ 



KEY 
. Neqotive pressure = -4% 
X Positive pressure = +47o 



TIME, hours 




REMOVAL OF RADON DAUGHTERS BY AIR CLEANING; 



The ventilation of 



underground uranium mines is the most effective means of con- 
trolling the amount of radon daughters in the mine atmosphere. 
High costs for ventilation have made methods for reusing con- 
taminated mine air more attractive, and the Bureau has done 
extensive testing of air cleaners using filter media to remove 
the radioactive particulates from air at flow rates up to 3,000 
cubic feet per minute (cfm). The tests show that certain types of 
filter media remove most of the radon daughters. A Bureau con- 
tractor is now developing an air cleaning system with an upper 
capacity of 10,000 cfm using clusters of filter cartridges that 
are cleaned continuously by reverse jets of compressed air. Upon 
completion, the air cleaning system will be tested in the Bureau's 
experimental uranium mine and in an active uranium mine. 



43 



■«^li!^^. 



Ground Control 



W^^ilfJi: 






'm-%k 



Major Problfem Are 

• Roof famjies 

• Faul4nP 

• Safe suppo(^ instf 

• Slope stab'i li ty 
t Waste disposal 



• P r e mi n i n g i jv^s^ s-'t i g a ti. 

• Mine desi fr\-C'i^ 

• Support sys'te'ms de^ 

:ilatio?\, 

• Hazard detefc1|Horf' and 
monitoring |:a^ 

• Waste dispotaT design 



The Bureau's GROUND CONTROL 
GRAM covers every phase of 
the danger of falling rock 



RESEARCH PRO- 

mining where 

or coal pre- 



sents a hazard to the miner. Ground con- 
trol problems continue to be one of the 
major causes of fatalities in underground 
mining, with falls of roof being the 
principal type of accident. Program ob- 
jectives include predicting hazardous 
geological conditions, the design of im- 
proved support systems, the development 
of monitoring methods, and the design and 
evaluation of equipment and techniques to 
keep miners out of potentially dangerous 
areas. Reduced miner exposure could be 
accomplished by remote, manually control- 
led bolters, remote controlled temporary 
roof supports, and instruments to deter- 
mine potentially unstable roof. 

Improvements in roof support may be 
available through an inorganic grout sys- 
tem for roof bolts, and a portable in- 
strument to determine the integrity of 
grouted bolts. The Bureau's full-scale 
roof bolt test facility is used to model 
mine roof behavior in order to evaluate 
alternative roof support systems under 
controlled conditions. 

The work on hazard detection includes the 
development and evaluation of techniques 
to detect changes in roof stability and 
to predict coal bumps, outbursts and im- 
pending roof falls. 



45 



ACCIDENT ANALYSIS : The Bureau of Mines regularly analyzes the 
ground-control-related accident reports issued by MSHA. The data 
extracted from these reports are used to plan, evaluate, and 
redirect Bureau research to assure that the 
upon problem areas in the world of mining. 



accident analyses also provide baseline data 
overall effectiveness of the research effort 
accident report analysis before and after 
research products by industry. For example. 



research will impact 

The results of the 

for evaluation of the 

through comparison of 

the application of 

the increased use of 



the longwall system of mining has brought with it unique ground 
control problems and accidents. Data from 1977 show that 77 per- 
cent of the ground-control-type longwall accidents occur at the 
face itself, as opposed to the T-junction (14 percent) and entry 
(9 percent) . 





HAZARDOUS GEOLOGIC STRUCTURES : A close correlation between geo- 
logic structures and roof failure was established from a study 
conducted at the Grove Number 1 Mine in Somerset County, Pa. A 
majority of the severe roof falls in the mine were found to be di- 
rectly related to the intersection of clay veins (illustrated) and 
associated slickensides in the roof. These potentially hazardous 
geologic structures, if persistent, can be extrapolated into adja- 
cent unmined areas in order to determine if and where they inter- 
sect other such structures. An instructional handout prepared to 
assist operating personnel to identify, map, and support trouble- 
some geologic structures in the mine is in use at the mine. In 
addition to that handout, an expanded and illustrated version is 
being compiled to assist operating personnel to recognize and 
identify the major hazardous geologic features occurring in mine 
roof throughout the Appalachian Region. 



46 



CORE BOOK : The Bureau has produced a book titled, "A Guide to 
Cored Rocks in the Pocahontas Basin," for use in accurately iden- 
tifying and logging drill core from the Pocahontas Coal Basin in 
southern West Virginia. This guide (illustrated) will help stand- 
ardize the logging of drill core from mine roof rocks and make 
possible the precise identification of rock types. Thus, by means 
of accurate core logging the maximum geological information can be 
derived from drill core, which is used in ground control studies 
for many purposes, and especially for studying the structure and 
composition of mine roof and overburden. The book is pocket- 
sized, has weatherproof pages, and contains a color-coded key for 
easy identification of basic rock types. The color photographs 
show the appearance of drill core in both wet and dry condition. 
A numerical code for each rock type is provided for computer stor- 
age and processing of drill core data. • This book is being widely 
used by industry. 





BOREHOLE GEOPHYSICS : Two new borehole logging systems are being 
developed in response to specific safety problems in the mining 
industry. Acoustic logging sondes (sounding devices) are used to 
gather information on lithology, rock strength, and elastic pro- 
perties for mine design. Existing systems require a fluid filled 
borehole to transmit and receive seismic energy. In many areas 
the technique is unusable because the ground water table is below 
the strata of concern. A dry hole acoustic logging system has 
been developed that couples directly to the borehole wall. The 
logging system can determine compressional (p) and shear (s) wave 
velocities to characterize each interval of rock in wet or dry 
boreholes. Duplicate systems can be fabricated by Southwest 
Research Institute. 



47 



IN SITU STRESS MEASUREMENTS : The rock stress measurement systems 
and techniques that have been developed by the Bureau of Mines can 
often be very important to the planning and development of new 
mines as well as the analysis of ground control problems in exist- 
ing mines. As mining gets deeper and the deposits more difficult 
to mine, a knowledge of the in situ stress field becomes essen- 
tial. Recent studies have shown that the horizontal stress field 
is continuous and predictable over rather large areas. The accom- 
panying figure shows the average horizontal roof stress that was 
determined to exist in five mines in the Beckley coal seam near 
Beckley, W. Va. High horizontal stresses are the source of numer- 
ous ground control and roof fall problems. The stress measurement 
equipment that has been developed by the Bureau, is now commer- 
cially available and is being used by mining companies, government 
agencies, and geological and engineering consulting firms. 



-3,223 psi , 
-2,403 psi , 




N 57° E 
N 33°* 



N 61 
N 29° 



■1,853 psi, 
- 1363 psi , 



' Mine B 
-3,14 1 psi 
- 1,775 psi 



N 47 W 
N 43° E 



N 71 
N 19° 



-3,255psi,N 68° E 
-2,339 psi, N 22° W 
C 

■ E 
W 



Scale, miles 




BOREHOLE SHEAR STRENGTH TESTER : Hardware and procedures were de- 
veloped for rapidly determining the inplace shear strength of 
coal. The hydraul ically operated device is permissible, portable 
and can be used in 3-inch boreholes at depths up to about 100 
feet. Field tests in a variety of mines, coal, nonmetallic, and 
hardrock, show that the tester is practical for mine use, espe- 
cially where recovery of unbroken core for laboratory tests would 
be difficult. In addition to eliminating the "good rock only" 
bias inherent in laboratory testing, this device offers the ad- 
vantages that many tests can be quickly performed in a single 
borehole with immediate results. Test data from four different 
coals and four rock types were equivalent to those from conven- 
tional tri axial tests. The shear strength of coal and rock is im- 
portant in determining pillar crushing, floor heaving, overburden 
collapse, roof bolt anchorage, and cutability and drillability of 
the materials. 



48 



MICROSEISMICS APPLIED TO COAL AND NONCOAL MINE SAFETY : Microseis- 
mic techniques of structural stability analysis have been applied 
to coal mine failure problems since 1971, with particular emphasis 
on problems associated with coal mine bounces, outbursts, roof 
falls, pillar stability, longwall mining geometries, and compar- 
ison of the stability of various mining systems and their support 
requirements. The energy, location, and number of rock noises em- 
anating from a mine area can be analyzed by various Bureau instru- 
ments to assess the stability of the area. In recent field exper- 
iments concerned with roof falls and outbursts the Bureau has been 
particularly successful in using a normalized energy per event an- 
alysis to detect sharp anomalies prior to the occurrence of fail- 
ure. Previous Bureau work in metal /nonmetal mines has resulted in 
commercial systems available from Electrolab, Spokane, Wash., 
which are used in five mines in this country as well as at instal- 
lations overseas. 




/Optimized auger drill steel 
(4 ft sections) 




Drill, feed and 
anchor controls 



Var»e air motor/ 
feed driven 



HIGH-SPEED DRILL TO DETECT ABANDONED UNDERGROUND WORKINGS: 
Pennsylvania has passed strict new laws that require the dri 1 1 i ng 
of eleven, 36-feet long probe holes, every 6 feet of advancement, 
in areas of uncharted workings. Drilling these probe holes often 
takes two or more shifts, because of inadequate equipment and 
poor access to the working face. Recognizing the need for new 
equipment to meet these new drilling requirements, the Bureau of 
Mines has begun a program to develop a lightweight, high-speed 
probe drill. This new drill is designed to reduce the drilling 
time to one shift, works in either coal or rock, and can be 
transported by one man. To achieve this goal, the drill uses an 
expanding borehole anchor to fix the drill in place, a power 
feed, and quick-connect steel couplings. Preliminary tests show 
that these goals are achievable with a second generation probe 
drill that will be long-term, in-mine tested. 



49 



GEOPHYSICAL TECHNIQUES TO DELINEATE ABANDONEO WORKINGS : A Bureau 
in-house project is studying the application of pulsed radar 
sounding techniques to identify and position abandoned mines and 
geological fault structures. Measurements have been made under- 
ground and on the surface; faults and adits have been detected to 
a 50-feet depth in metamorphic, granite, quartz monzonite, and 
graywacke rock. Even deeper targets have been detected in lime- 
stone to below 100-feet. Data enhancement with time series analy- 
sis identical to that used in seismic exploration generally ex- 
tends the detection range an order of magnitude (10:1). This 
measurement technique should be helpful in drilling programs to 
identify three-dimensional coordinates for abandoned mines, fault 
structure, mineral zones in marginal mines, water filled struc- 
tures, and block caving boundaries. A Bureau Report of Investiga- 
tions, will provide fabrication and system utilization details. 





ROCK MECHANICS INSTRUMENTATION AND GUIDEBOOK :" Under a contract 
to the Bureau of Mines, a borehole extensometer with magneto- 
strictive (MS) type readout (illustrated) for measuring strata 
separation in coal mine roof was developed and is available to 

anchors set at dif- 

and the MS probe is 

A change in position 

between each set of an- 

several coal mines has 

to be useful for roof 

rock mechanics instru- 



each anchor, 
the layers 
device in 



industry. The extensometer has a number of 
ferent horizons in a borehole in the roof, 
used to detect the position of 
indicates strata separation in 
chors. Installation of the 
shown the MS type borehole extensometer 
stability measurements. A guidebook on 
mentation is being compiled. The manual will enable mine person- 
nel to quickly and effectively select the appropriate instrument 
to assess, monitor, and evaluate ground control problems, such as 
convergence, strata separation, groundstress, and support loads. 



50 



STRUCTURAL DESIGN COMPUTER PROGRAMS : During recent years, the 
Bureau has developed a number of computer programs to aid the min- 
ing industry in structural design problems. Each report describes 
specific research in problem areas of mine design, such as, "A 
Method for Computing Stabilization Pressures for Excavations in 
Incompetent Rock," RI 8128; "Analysis of Fracture Orientations for 
Input to Structural Models of Discontinuous Rock," RI 7669; "Com- 
puter Program for Pit Slope Stability Analysis by the Finite 
Element Stress Analysis and Limiting Equilibrium Method," RI 7685; 
and "A Computer Program for Generating Finite Element Models of 
Mine Structures," IC 8510. Several other reports address the 
problem of rock fractures and their association with structural 
failure in mines. Many requests have been made by the mining in- 
dustry for these reports and for assistance in adapting the prog- 
rams to a particular mining problem. Bureau engineers in many 
cases respond to these requests by giving assistance directly. 




^ s u Ji u 



s v 




AIR CONDITIONING CHAMBERS : Moisture in mine air causes gradual 
deterioration of certain exposed roof strata and may lead to 
failure by attrition or, possibly, more massive roof falls. The 
effectiveness of sealants in preventing roof slaking is recogniz- 
ed, but the application over great distances of entries is cost- 
ly. Another preventive method, the use of air conditioning or 
tempering chambers to control the moisture in the 
been used occasionally, but the results were not 

control technique. 

the Valley Camp No. 



it remained a controversial 
conducted an experiment at 
Wheeling, W Va., to evaluate 



intake air, has 

documented and 

The Bureau has 



1 Mine near 
air conditioning chambers and to de- 
velop design criteria. Underground measurements completed in 
1980 provide strong evidence that the roof in main entries and 
air courses can be protected from severe slaking by diverting in- 
take air through a series of chambers designed to provide ade- 
quate residence time to reduce humidity levels and fluctuations. 



51 



GROUND CONTROL STUDIES OF LONGWALL FACES : 
conducted ground control 



At the request of MSHA, 

the Bureau has conducted ground control studies at the following 
longwall operations: Old Ben No. 24 in Illinois, York Canyon in 
New Mexico, Somerset No. 60 in Pennsylvania, and Quarto No. 4 in 
Ohio. A major purpose of these studies was to develop a greater 
insight into the nature of strata activity surrounding an operat- 
ing longwall face (illustrated), to allow for a timely recognition 
of developing problems, and to improve the selection process of 
face equipment for subsequent longwall operations. Examples of 
collected during these studies include: face support load- 
gate road convergences, pillar and abutment loadings, and 
caving heights. The data collected have been used by at 
one operator. Old Ben Coal Co., to assist in the selection 
supports for a planned longwall. Another operator, the 
Coal Co., used the data to design the gate entry 



data 

ings, 

roof 

least 

of face 

North American 

systems for its 



longwalls. 





LONGWALL FACE STABILIZATION : This work concerned the stabiliza- 
tion of a high coal (9-foot) longwall face that was having signi- 
ficant face sloughing problems. The problems involved the insta- 
bility of large blocks of coal at the face and, as a result, falls 
of the cap rock above the coal. Underground trials were run using 
wooden dowel with resin cartridge and resin injection techniques. 
Face areas ranging from 90-to 140-feet were stabilized. Lengths 
of face ranging from 90-to 140-feet were drilled (illustrated) and 
stabilization techniques applied. The drill holes were approxi- 
mately 12-feet long by 2- inches in diameter. The wooden dowel 
technique successfully stabilized the face in areas where it was 
applied. The trials established the effectiveness of the tech- 
nique and indicated that full face stabilization offered signifi- 
cant advantages over partial face stabilization. 



52 



LONGWALL SUPPORT TESTING : A test frame was erected and a variety 
of load distribution tests run on a longwall shield type roof sup- 
port as shown here. The load ranges used during these tests were 
1,000,000 pound maximum vertical load and 300,000 pound maximum 



horizontal load. The test frame allowed 
application of both horizontal and vertical 
of these tests, design modifications were 
structure by the manufacturer. The tests 
the specifications of a test rig to be used 
The Bureau's test rig is now being used to 
roof support hardware. 



for the simultaneous 
load. As the result 
made in the shield 
served as a basis for 
by the manufacturer, 
test other types of 





SHORTWALL MINING DEMONSTRATION : Under a cooperative agreement 
between the Bureau and the Beth-El khorn Corp., a shortwall mining 
system (illustrated) was demonstrated at the Hendrix No. 22 
Mine. During the period January 1974 to January 1977, six short- 
wall panels were developed and approximately 600,000 tons of coal 
produced. System performance criteria included production, roof 
control, dust control, availability, productivity, subsidence, 
and cost. The shortwall system outproduced the most effective 
room and pillar section in the mine by 100 tons per day. This 
increase in production did not offset, however, the increased 
capital cost of the shortwall equipment, when considering the 
profitability of the two mining systems. On average, the recov- 
ery factor experienced by the shortwall method was equal to that 
realized by a room and pillar section utilizing filler extrac- 
tion. The results of the shortwall demonstrations have been doc- 
umented in the technical literature. 



53 



SINGLE-ENTR IES: 
Bureau and 



A recent 7-year cooperative agreement between the 
Xaiser Steel Co. demonstrated a single-entry develop- 
ment system for longwall mining. The first single-entry had an 
incombustible center wall attached to a spaced wood crib support 
row, creating a headgate and tailgate for two adjacent longwalls. 
A second single-entry, constructed without the center wood crib 
supports, served as a headgate for the second longwall panel, and 
was driven at twice the rate of conventional two-entry systems. 
No development problems were encountered, however, the wood crib 
support wall did not adequately maintain the tailgate section of 
the dual entry, and additional support was necessary. Experimen- 
tal steel-fiber reinforced concrete cribs that replaced a section 
of wood cribs reduced excessive roof and floor convergence and 
created an effective tailgate thus demonstrating the feasibility 
of double-gate, single-entries. These Bureau-developed cribs are 
nearing commercialization, with several fabricators interested in 
production. They are cost-competitive with the wood cribs, non- 
flammable and longer lasting. 





OUTPUT TORQUE INDICATOR : Under Bureau contract, both pneumatic 
and electronic torque thrust control systems to tighten mine roof 
bolts were developed. Both systems were designed to retrofit mine 
bolting machines and automatically torque roof bolts to a prede- 
termined set torque, using a fast speed for bolt rundown and a 
slow speed for final tightening. A gage shows the torque on each 
bolt tightened. The pneumatic system has been laboratory and 
field tested and the electronic system laboratory tested. Conven- 
tional bolters often have torque variations of ± 30- to ± 40'-per- 
cent. A threefold increase in torquing accuracy for both systems 
was achieved, resulting in torque variations of only ± 8 percent 
by the electronic system and ± 6 percent by the pneumatic system. 
Long-term testing and evaluation are now underway. 



54 



FULL-SCALE MODEL ROOF BOLT TEST FACILITY : A full-size model of a 
coal mine entry has been built; it consists of two, 3-by 6-by 15- 
feet supporting pillars separated by a clear span of 15-feet and 
capped by six roof slabs, 1-by 15-by 21-feet. Surrounding a 90- 
cubic yard, 5000-psi concrete entry is a 150-ton structural steel 
reaction frame supporting a servo-controlled hydraulic loading 
system. This system is capable of applying about 3 million pounds 
vertical and 1.8 million pounds horizontal, with vertical and 
horizontal shear capabilities of 0.5- and 0.9- million pounds. Hy- 
draulic supports in the mine entry are capable of furnishing pre- 
mining and postmining support. Parameters such as strain in the 

types of bolts, slab deflection, 

interlaminar slip between the 

the model can be moni- 

acquisition system will 



bolts, 
strain 
slabs, 
tored. 



total load on certain 

within the slabs and pillars, 

and temperature within and around 

A minicomputer control and data 



completely control the testing operation on a real-time basis. 





PERFORMANCE OF EXPANSION-SHELL ROOF BOLT COMPONEMTS : Laboratory 
tests were run to determine the effect of component performance, 
bearing plate, and anchor on the performance of the roof bolt as- 
sembly. The bearing plate studies investigated the relative ri- 
gidity of flat, bell, and doughnut type plates under loads up to 
15,000 pounds. The anchor studies investigated the effect of an- 
chor type, rock type at the anchorage horizon, installed tension, 
borehole roughness, rate of torquing and relative humidity fluctu- 
ations on the performance of a rock-anchor system. As a result of 
these investigations, performance criteria were developed and 
transferred to the coal industry through a variety of publica- 
tions; examples include changes in the procedures for the pull 
test and modification of the stiffness characteristics of the 
bearing plates. This information is used by industry in develop- 
ing roof control plans. 



55 



ROOF BOLT TENSION MEASUREMENT : The mining industry and the mine 
inspection force long have had the requirement of a low-cost meth- 
od of measuring installed roof bolt tension and changes in roof 
bolt tension with time. In a cooperative program, the Bureau of 
Mines and NASA developed an ultrasonic system that measures the 
installed bolt load without the need for additional, expensive 
hardware. This system measures the installed bolt tension simply 
by means of placing an ultrasonic transducer against the bolt head 
during tensioning. The technology is being adapted from technol- 
ogy in the space program, and will be used to verify uniform roof 
bolt tension, thus leading to improved ground control. 




STRESS, ksi 




EVALUATING RESIN-GROUTED ROOF BOLTS : Currently, there is no ac- 
ceptable method of nondestructively testing or evaluating the in- 
tegrity of an installed resin grouted bolt. In order to detect 
improper installation of resin grouted bolts, the Bureau has de- 



veloped an ultrasonic method 
consists of sending a burst 
reflecting off the back of 
back at the head. If the 
length of the bolt, most of 
and reflected back will be 
the surrounding rock; thus 



of evaluating resin roof bolts, that 
of ultrasonic energy down the bolt, 
the bolt, then receiving the energy 
resin has hardened along the entire 
the energy transmitted down the bolt 
radiated through the resin and lost to 
the energy received at the bolt head 



will be low. If the resin has not set up, or if the resin has 
been forced out into cracks, a smaller portion of the energy 
transmitted will be lost to the rock; and this case, the energy 
received at the head will be high. The laboratory version of the 
tester is being simplified for extended underground testing. 



56 



FULL-COLUMN RESIN BOLT DESIGN CRITERIA : Because of the increased 
applications of resin bolts for roof control in domestic coal 
mines, the Bureau has been engaged in investigations of the me- 
chanics and effectiveness of resin bolting systems and in devel- 
opment of design criteria for bolting plans. When completed, 
these efforts will provide comprehensive documentation of litera- 
ture, field observations, laboratory test data, and theoretical 
information, as well as recommended design criteria. Field tests 
were conducted at the Powhatan No. 4 and No. 7 Mines of the Quarto 
Mining Co., (North American Coal Co.) to evaluate the relative ef- 
fectiveness of different roof bolting systems. The company has 
adopted the nontensioned, full-column, resin bolting system as the 
primary means of permanent roof support for the Powhatan No. 7 
Mine. As a result of these studies, the vertical and nonvertical 
force systems acting on a full-column resin bolt were documented 
and small scale laboratory tests to investigate the potential ef- 
fectiveness of nontensioned bolt types were defined. 





INORGANIC GROUTS FOR COAL MINE ROOF BOLTS 



The Bureau is develop- 
a full-column bolt that replaces the resin 

A mixture of the 



ing two variations of 

with more economical gypsum plaster and water, 
dry powder with accelerator and pinhead-size water droplets en- 
cased in waxy globules is prepackaged in sausage-shaped car- 
tridges. When the cartridges are inserted into a drilled hole, 
the bolt is inserted and slowly rotated to penetrate the car- 
tridges and crush the microcapsules of water, forming a viscous 
paste as the bolt advances. The accelerated plaster then sets 
within 2 minutes or less. These cement-anchored bolts are now be- 
ing evaluated for MSHA approval as the sole means of roof support. 
The Bureau was granted an IR'IOO Award in 1980 for this develop- 
ment. Another concept involves filling the bolt hole with plaster 
slurry before bolt insertion. The Bureau has several contracts 
for developing equipment to store, measure, mix, and inject the 
slurry one hole at a time in a self-cleaninq operation. 



57 



EXISTING AND INNOVATIVE ROOF BOLT ELEMENTS : Since their introduc- 
tion to the mines in the early 1960's, full-column resin bolts and 
the numerous modified resin-grouted roof support mechanisms have 
been the object of numerous investigations by the Bureau. How- 
ever, until now, tests have never covered a comprehensive range of 
bolt types and bolt properties versus rock properties. The objec- 
tive of this work is to produce a table of significant resin 
grouted bolt properties for each of the commercially available 
bolt types in numerous host rock mediums. The bolt properties se- 
lected as being most significant from a roof support design point 
of view were ultimate strength of the system and average stiff- 
ness, for both tensile and shear loadings. The ultimate strength 
is defined as a measure of the maximum load that a bolt can carry, 
and stiffness, a measure of the flexibility of the system defined 
as load required for 1 inch of elongation. (Modulus of elasticity 
cannot be determined for these systems since the effective area 
cannot be defined.) 





DEVELOPMENT OF LIGHTWEIGHT HYDRAULIC SUPPORTS : Hydraulic props 
are used where supports are needed to eliminate the hazard of un- 
supported roof. Present supports, such as jacks, hydraulic props, 
wooden posts, and crossbar sets, are heavy, time consuming to in- 
stall, and often not fully utilized even though the unsupported 
constitute a potential threat to the miner's life. The 
of the lightweight hydraulic support was fabricated 
poppets and oil passages to eliminate flow restriction 
The free flow of hydraulic fluid enables the miner to 
prop a maximum of 2 feet in 10 seconds to provide fast 
contact. Commercially available hydraulic props 
tons in 6-to-8-feet of underground openings weigh 
pounds. The total weight of the lightweight 
is 55 pounds including hydraulic fluid. The 
self-contained with an integral hand pump, over- 
and ring, and release for remote lanyard removal, 
fabricated for long-term field evaluation. 



ground may 
pump block 
with large 
problems, 
extend the 
roof- to- floor 
that support 22 
approximately 100 
hydraulic support 
prop is totally 
load relief valve 
Forty props are being 



58 



MECHANICAL SCALING BAR : A powered, handheld scaling bar is being 
developed under a Bureau contract. The prototype bar, constructed 
of aluminum tubing attached to a small air hammer, has been tested 
in the laboratory and a rock quarry. Although specifications were 
met, blow-energy losses through the bar prevented successful scal- 
ing of the quarry face. The unit is being redesigned to increase 
blow energy, without increasing the weight, and will be reevalu- 
ated during 1981 . 



|pi- 





RETREAT MINING SUPPORT SYSTEM : A Bureau contractor has designed, 
fabricated, and demonstrated a temporary, mobile roof support 
machine (MRS) for retreat mining. The MRS machine permits setting 
and removal of breaker or turn posts, remotely; it reduces the 
time and labor required to set and move temporary supports, and 
provides nonyielding support that is superior to wooden posts. 
The MRS has successfully completed the required 20 production 
shift trials at a mine and will undergo an additional 3-month 
testing. The MRS has gained the acceptance of management and 
miners at the demonstration mine. A second-generation machine is 
being designed, based on the experience gained in testing the 
first prototype. Both the manufacturer and the cooperating mine 
will share in the cost of these second-generation machines. 



59 



LOMGER-THAN-SEAM-HEIGHT DRILL : Fall -of- roof is the most frequent 
cause of fatalities in underground coal mines. Placing permanent 
support (roof bolts) is especially difficult where the length of 
bolt needed exceeds the seam height. To aid in this task, the Bu- 
reau began the development of drills for longer- than-seam-height 
bolt holes, which would not require the operator to change drill 
steels. Several prototypes were designed and fabricated. As the 
productivity advantages became more evident, the projects were 
transferred to the Department of Energy for completion. Two 
drills are now nearing the end of long-term endurance testing; 
these form the basis for new Bureau projects for safe, remote- 
controlled bolters. 





IMPROVING SURFACE COAL DISPOSAL SITE INSPECTIONS : To determine 
the feasibility of aerial photogrammetry Tn supplementing MSHA 
ground inspections, 15 coalwaste piles in West Virginia and Ken- 
tucky were studied. For 10 months targets set off from the waste 
dumps were monitored. Elevations were computed onto an imaginary 
grid system covering the entire waste area to show the changes oc- 
curring between the monthly flights. A difference in vertical 
readings indicated a horizontal movement or embankment creep, a 
condition difficult to verify with ground inspection. The aerial 
survey was supported with quarterly ground surveillance of the 
sites. Both MSHA and the cooperating mines favor the use of aer- 
ial monitoring of surface coal disposal sites and anticipate more 
use of this technique in the future. 



60 



ROCK PRECONDITIONING TO PREVENT ROCK BURSTS : An entire st oping 
area between two levels of Hecla Mining Co.'s Star Mine in Burke, 
Idaho is being drilled, lightly charged, and blasted to destress 
or precondition the rock before mining. By this method, long 
holes are drilled into the floor, sill, pillar, and first level of 
the stope before development, and then lightly charged and blasted 
to destress or precondition the rock before mining. A down- 
the-hole type pneumatic drill (at 250 psi air pressure) penetrates 
the hard quartzite at a rate of about 12 inches per minute; the 
preconditioned zone will be 200 feet vertically and 450 feet lat- 
erally on the 7900 level; holes are 4-inch diameter and up to 100- 
feet deep. In cooperation with Hecla Mining Co., a Bureau con- 
tractor will monitor changes in rock stresses, seismic velocity, 
and displacement across the destressed zone as mining progresses. 




__^-^Geophor\e 



i I I ; I 
M ! 



i I I i 111 





!! Ilillllui < 



APPLICATION OF ROCK BURST TECHNOLOGY : Bureau research using mi- 
croseismic methods to study rock bursts in mines has shown that 
burst-prone mine structures can be monitored successfully to de- 
termine where rock bursts are likely to occur. In some instances, 
warnings of impending failure can be given so that personnel can 
be warned and withdrawn from burst-prone areas. Control measures, 
such as destressing by blasting, have been shown to be effective 
in altering burst-prone areas so that rock bursts either occur at 
a predetermined time or are avoided entirely. Typical destressing 
patterns applied in known burst-prone pillars have proved an ef- 
fective means of controlling bursts. Current ongoing work is 
aimed at improving the predictive capabilities of the methods so 
that they may be used more reliably, and at understanding the ef- 
fects of destressing on the load conditions in the remaining 
structure. Commercial microseismic monitoring units are now in 
use in all the rock-burst-prone mines in the Coeur d'Alene deep 
silver mining district. 



61 



LMC LAGGING : A Latex-Modified-Concrete (LMC) lagging, developed 
as a substitute for wood lagging, consists of a mixture of latex, 
cement, sand, and lightweight aggregate, which has greater 
strength and flexure than ordinary concrete. The Bureau-developed 
LMC lagging is designed to withstand the same loads as dry wood, 
and has been field-demonstrated at several mines. At one mine, LMC 
replaced wood in a timber repair job; at another mine, it was used 
in a new support system featuring steel arch sets with pea gravel 
backpacking. Performance is good at both mines. LMC has the fol- 
lowing advantages over wood: nonflammabil ity, rot resistance, and 
no reduction in strength from moisture; its disadvantages are 
greater weight, difficulty in framing, and, at present, higher 
cost. The latex additive for concrete is available from the Dow 
Chemical Co. 



■ 


^K" 


"^^H^B 


* / 


1 


^IPi^^^^^^K 




i 


f 


^■t* 


^"JF 


t 


'd 


^1 







"-TF--^ 




GROUND SUPPORT SYSTEMS— BLOCK CAVE MINING : Under a cooperative 
agreement, the Bureau is testing steel sets with various types of 
lagging such as wood, channel iron, and latex-modified concrete at 
the Magma Copper Co.'s San Manuel Mine. The sets are backpacked 
with sand/pea gravel to prevent point loading on the members. Re- 
sults are encouraging; no structure failure has occurred. The 
test is being expanded to a fringe drift in heavy ground. 



62 



ELECTROKINETIC TREATMENT OF MINE WASTE : Three field tests, in co- 
operation with the Hecla Mining Co., successfully demonstrated 
that slimes can be dewatered and consolidated into firm, dense 
backfill by application of high-voltage, direct electric current. 
This method not only utilizes the waste more efficiently but elim- 
inates the need for tailing dams which are costly to build and 
maintain, and ecologically troublesome. AMAX, Inc., with Bureau 
assistance, effectively consolidated slimes by means of electroki- 
netic treatment in a 100-by 20-by 6-feet deep settling basin at 
the Henderson Mine in Colorado. Henderson engineers are planning 
improved permanent systems in one or two settling basins. 





Another Bureau-sponsored project has developed safety practices for 
the electrokinetic process underground. Successful field demon- 
strations of the electrokinetic consolidation of metal-mine wastes 
have led to laboratory testing of these procedures on fine-grain 
coal waste. Results show that most of the sludges can be convert- 
ed into a firm cohesive product with moderate power consumption. 
Full-scale field testing began in late 1979 under a cost-sharing 
agreement with the Clinchfield Coal Co. A clamshell dredge trans- 
fers sludge into two, 200-cubic yard concrete cells on the banks 
of an old disposal pond. Power from a 600-kw rectifier applied to 
horizontal iron grids, at the top and bottom of the sludge, devel- 
ops a firm product that can be used as fuel or fill. A 30-day op- 
erating period, demonstrated a weekly production capacity of about 
1,000 tons of cake with a 79-percent solids content for a power 
cost of 50-to 60-kwhr per ton of cake. 



63 








m 



m 

r ■; 


i^H 


t 


'1 



1 



/ 



The INDUSTRIAL HAZARDS RESEARCH PROGRAM covers a 
wide range of problems related to improving the 
safety of mine personnel that are not covered by 
other Bureau programs. Effort is directed to re- 
ducing the hazards related to human factors, in- 
cluding education and training, and to failures or 
inadequacies in equipment and techniques, that is, 
electrical, mechanical, illumination, communica- 
tions, and materials handling. 

Under this program new mining machinery is being 
designed specifically with operator safety as the 
integral feature. Existing equipment is being 
retrofitted with such devices as protective canop- 
ies and optimized operator compartments. Individ- 
ualized training systems and "hands-on" training 
equipment are being developed for safety training 
of mine personnel. 

The Bureau has emphasized the development of under- 
ground communications and illumination systems. 
Underground monitoring and communications systems 
have been designed and built to monitor face, sec- 
tion, and haulageway air, and to provide through- 
the-earth emergency communications. 



Major Problem. #eas t Approaches 



• Man -machine interfa{ 

• Training 

§ Electrical hazards 

• Poor^ i LI ami n ati on 

• Underground commun-ic 
and moni toring ^^ 

• Equipment and haulag 
accidents 



• Human factors 

• Training systems 

t Electrical systems 

• Equipment design 
Illumination 

• Haulage and materials 
handling 



Research is u 
dealing with 
tenance of el 
are being de 
dieting failu 
A protective 
troll eyline-t 
high current 
for mine haul 



nderway to provide better methods for 
the installation, repair, and main- 
ectrical systems. Monitoring systems 
veloped to yield information for pre- 
re of cables and electrical equipment, 
device for detecting low-current 
o-ground faults in the presence of 
loading was designed and demonstrated 
age systems. 



64 



HUMAN FACTORS IDENTIFICATION OF PROBLEMS IN SURFACE MINES : Human 
error continues to account for or contribute to a substantial pro- 
portion of all fatality- and injury-inducing accidents in surface 
mines. Many of these accidents can be traced to poor human fact- 
ors design of jobs, workstations, maintenance procedures, and 
training. Therefore, the objectives of this effort are to iden- 
tify human factors problems associated with high accident and 
injury frequencies and to recommend appropriate technology trans- 
fer or further research in order to improve identified problems. 
The report produced as a result of this research will serve as a 
guide and planning document to establishing surface mining human 
factors research priorities. 





r^ BIOMECHANICS OF LOW COAL : Very specialized equipment has been 



developed for use in low coal, but little consideration has been 
placed on the problems encountered by miners when working in low 
coal. For example, there is a lack of adequate data on the 
effects of restricted work spaces on the performance of mining 
operations. The objectives of this project are to evaluate the 
job demands associated with low coal mining, to survey the 
anthropometry, strength, and physical work capacity of low coal 
miners to determine if they differ from the U.S. population, and 
to recommend, on the basis of the available information, how job 
and work station design for low coal mining can be improved. To 
meet this objective, an analysis of low coal mining tasks is 
being performed to establish overall physical demands on job per- 
formance. Recommendations will then be made to optimize the 
designs of low coal mining equipment from the standpoint of human 
factors considerations. 



65 



PERSONAL EQUIPMENT IN LOW COAL : A simulated low seam mine was 
constructed to test alternative personal equipment designs. Lab- 
oratory and simulator studies were used to evaluate retroreflec- 
tive outer garments, coiled cap lamp cords, padded gloves, low 
profile helmets, size and weight of battery pack, battery pack 
belt concept, improved knee pads, and slip-resistant rubber boot 
sole designs. To date, results have indicated that: (1) the 
weight of a battery pack is more important than size in terms of 
work performance; (2) an optimal configuration of retroreflective 
material can significantly increase conspicuity of miners; (3) in- 
corporating coiled cord into the cap lamp can reduce the frequency 
and severity of cord snagging accidents; and (4) gloves can be de- 
signed to increase protection without affecting manual dexterity . 
Improved knee pads and boot soles were designed and will be fabri- 
cated and field tested for 5 months as part of this project. 





COST INDICATION FOR MINING ACCIDENTS : The Bureau has developed 
a model for estimating the tangible costs of injury-causing 
accidents in underground bituminous coal mines. The model sum- 
marizes the monetary cost to the mining companies, to the miner 
and his family, and to society. Costs in these categories are 
subgrouped by mining activity at the time of the accident, by 
type of accident, and by the degree of injury; costs can be 
compiled by mining activity, regular job title, nature of the 
injury, mining method, type of accident, and degree of injury. 
The model can be used to determine trends in accident costs and 
to evaluate the effectiveness of new safety programs and pro- 
cedures. A post-accident product loss model has recently been 
added. Preliminary studies using the model have shown an aver- 
age annual loss in mine productivity of 2.6 percent jfO.9 per- 
cent as a result of accidents. 



66 



MINE RESCUE TEAM TRAINING MATERIALS : At present there is a great 
deal of mine rescue team training throughout the United States. 
The number of teams available and the number of teams that will be 
conducting training is expected to increase in the near future ow- 
ing to the promulgation of Code of Federal Regulations (CFR), Tit- 
le 30, Part 49. This law will require the establishment of or ac- 
cess to mine rescue teams for each underground mine in the Nation. 
It also outlines training requirements for each team member. A 
contract was let to develop and evaluate these training materials 
for mine rescue team members. Following the development of these 
materials, seminars will be held for the purpose of distribution 
and instruction concerning use of the training materials. 





REVIEW AND EVALUATION OF CURRENT TRAINING PROGRAMS: 



To evaluate 



the general effect of safety training on accident and injury ex- 
perience in the coal mine industry, a survey was made of current 
mine training programs and their effectiveness in reducing the 
frequency of mine injuries. Mines were ranked according to the 
overall effectiveness of their training. Programs evaluated as 
most effective were analytically compared with programs that were 
apparently less effective. According to the findings, management 
philosophy and commitment to training are key factors in accident 
reduction through training. Results of the study have been used 
by MSHA in the recent preparation of mandatory training regula- 
tions (CFR, Title 30, Parts 75.200 and 77.200). Mine companies 
that participated in the Bureau research project have used the 
results to assess their own company-sponsored training, and to 
improve training resources. 



67 



TRAINING PROGRAf^ FOR FIGHTING SMALL FIRES : Fire situations in un- 
derground mines differ very widely from surface fires; additional 
hazards are posed owing to the presence of toxic and explosive ga- 
ses, smoke rollback, bad roof and floor conditions, and difficul- 
ties in communication and accessibility to necessary firefighting 
equipment, and the longer time to evacuate the personnel from 
underground mines. The severity of this hazard has been recog- 
nized while formulating the training program. The task elements 
involved are chiefly assessment of training needs, and development 
and evaluation of the scenarios including hands-on training pro- 
grams. Specifically, programs are being developed to train miners 
to recognize the exact nature of the fire situations, in order 
that they can make rapid judgment decisions on the extinguishing 
methods for small, localized fires. 





TRAINING SYSTEM FOR MINE HOIST OPERATORS : Past and ongoing safety 
research has been directed toward the development of improved 
hoisting control and monitoring systems, brakes, safety devices, 
and safeguards. To complement and maximize the benefits of these 
efforts, a need has existed to improve present methods of hoistman 
training. Such a program has been developed by the Bureau. The 
training program consists of self-paced, individualized materials 
that can be used to support and structure existing methods of on- 
the-job training. The course familiarizes the trainee with basic 
hoist operation concepts through the self-study texts, deals with 
the specific characteristics of the hoist that the trainee will 
operate, and finally permits the operation of the hoist under the 
supervision of an experienced hoist operator. 



68 



CONTINUOUS MINER TRAINER : The Continuous Miner Trainer is a stand- 
alone training device for part-tasks and procedures training in 
various elements of coal mining operations. Through practice with 
the trainer, the operator trainee can gain familiarity with the 
operating procedures, controls, and the mining application of a 
typical continuous miner in the following aspects of coal mining 
operations: tramming and turning, positioning for coal removal, 
sumping and face cutting, turning a crosscut, and positioning the 
conveyor for shuttle car loading. The training device consists of 
an operator's station containing actual hydraulic and electric 
controls from a real continuous miner, a computer system, graphics 
display terminal, sound generators, a rear and a forward slide 
projection system, and an instructor's console. The manipulation 
of the controls by the trainee results in the movement of the con- 
tinuous miner, projected on the graphics terminal, in approximate- 
ly the same manner, rate of response, and with the sound as would 
be experienced on the continuous miner during actual operation. 





ROOF BOLTER OPERATOR TRAINING: 



Accident 
roof boltin 



that the risk of injury to 
been significantly greater than to operat 
derground face equipment. Occupational 
risk of injury from the equipment itself 
risk of the all -too- often serious injury 
Instructional strategies and training mat 
Bureau contract, are designed to impart 
knowledge to assist the mining industry i 
training practices, and involve slide/ta 
ualized workbooks, on-the-job checklists 
with the actual equipment. This training 
task training, to train new miners, or as 



statistics have indicated 

g equipment operators has 

ors of other types of un- 

hazards include both the 

as well as the inherent 

from roof and rib falls, 
erials, developed under a 

the necessary skills and 

n upgrading their present 

pe presentations, individ- 

, and supervised practice 

can be used to support 

a refresher program. 



69 



MICROPROCESSOR BASED INSTRUCTION : The Bureau of Mines is invest- 
igating the application of microprocessor-based instruction to 
mine vocational training. A typical system includes a CRT screen, 
keyboard, and microcomputer in conjunction with a random access 
slide projector. The student is presented with material adjusted 
to his competency level and is continually participating in the 
lesson, thereby improving student motivation; this lends itself to 
a highly efficient teaching method. To enable mine instructors to 
write the course lessons, deliverable on the teaching system, the 
Bureau is preparing an authoring procedure. Commercially avail- 
able microprocessor-based interactive teaching systems are pre- 
sently being evaluated in the mining community. It is anticipated 
that these systems will contribute to the upgrading of miner 
training. 





MINE POWER DISTRUBUTION : The radial system commonly utilized in 
underground mining, when compared with other possible distribution 
schemes, such as loop systems, with respect to cost, operating ef- 
ficiency, and safety was shown to be superior in cost and safety. 
The conclusion was reached that 7,200 volts is the optimum distri- 
bution voltage. An interactive computer "model" of a mine power 
system, developed to aid in electrical system design and in 
short-circuit calculations, is now being adapted for use on 
minicomputers. The modeling capabilities include load flow, 
balanced fault, and general fault computation. The program 
output is in terms of real and reactive currents and voltage drops 
at all buses. Application notes on various power system subjects 
have been prepared for distribution to mining personnel; the 
notes, thus far, cover cable fault location, ground bed construc- 
tion, and cable splicing. 



70 



PERMISSIBLE ELECTRICAL EQUIPMENT : Any electrical equipment that 
is used in potentially explosive mine atmosphere must be certified 
by MSHA as permissible, that is, either housed in an explosion- 
proof enclosure or intrinsically safe. Extensive research has 
been conducted to provide MSHA the necessary information for their 
present certification process as well as for proposed regulations; 
this has consisted primarily of providing baseline data and devel- 
oping performance standards to replace the present design regula- 
tions. Bureau research has also led to the development of innova- 
tive hardware for explosion-proof enclosures. This hardware con- 
sists of a quick-access cover, grommet-type, elastomeric stuffing 
gland, and a pressure vent, that is the most innovative concept. 
It has been shown that the vent can reduce internal pressures of 
an enclosure from 90-to 5-psig. An experimental permit was issued 
for this vent by MSHA and it will be field tested. 





U ^ 



CABLES: Temperatures and other factors that affect cable rating 
have been evaluated and the data used to prepare recommended cri- 
teria for rating cables and setting protective devices where ca- 
bles are used in high intermittent load conditions, such as on a 
continuous miner. Problems with hydraulic cable reel systems may 
be overcome with the use of an all-electric reel 
in the concept design stage. Performance, cost, 
tors affecting the choice of shielded cable in 
operations have been investigated and summarized. 
of the State of West Virginia, a study was conducted on the re- 
sponse of fuses and circuit breakers when an arcing fault occurs 
in a dc trailing cable. Electrical safety information developed 
by the Bureau is continuously supplied to MSHA, mine personnel, 
and equipment manufacturers. Much of this data has been used by 
MSHA to prepare revisions proposed for Federal Safety Standards. 



system currently 

and safety fac- 

underground face 

At the request 



71 



TRAILING CABLE SPLICES 



A new method of laboratory testing 



splices, utilizing a track- guided cart that closely simulates 
movement of a shuttle car past a tie- point, has revealed inter- 
esting facts about splice life. For example, precise dimensioning 
of conductors is less important than previously considered, be- 
cause of length equalization as the conductors move inside a long 
cable. A current program on cable splices includes evaluating 
splices cut out of cable discards at the mines and communicating 
to the mine personnel the researchers' findings of good and bad 
points of workmanship. Splice components developed include spe- 
cial crimp sleeves for power, ground, and pilot conductors. 





TRAILING CABLE FAULT LOCATION 



Current procedure for locating 
to apply a high level of electric 
at the site of the fault. The 
unsafe, and in the case of high 
does not work. The Bureau of 



faults in trailing cables is 
power to blow a hole in the cable 
procedure is not only crude but 
resistance faults it frequently 
Mines undertook research to develop safe, portable devices that 
locate faults accurately and rapidly. Bureau contract and in- 
house projects so far have produced fault detectors based on in- 
frared, electromagnetic, and time domain reflectometer (TDR) tech- 
niques. Three manufacturers have recently marketed electro- 
magnetic locators based on an original Bureau design. An auto- 
matic TDR locator, providing microcomputer control, has been suc- 
cessfully tested in the laboratory and is now undergoing extensive 
field trials. 



72 



CIRCUIT PROTECTION DEVICES : A "handbook" approach to ground fault 
and overcurrent protection, specifically directed toward mining 
applications, is under development. This study primarily concerns 
ac distribution but is supplemented by other work on dc systems. 
As part of the program, a tester assembly for circuit breakers in 
distribution systems was developed that has simplified evaluation 
techniques. Methods of assessing the reliability of protective 
devices have been developed; and data are being gathered from co- 
operating mines in order to complete the assessment. Maintenance 
scheduling procedures will be forthcoming from this program. One 
of the more novel items that the study provides is a technique for 
allocating spares in an optimum manner for such consumable items 
as trailing cable splice kits and light bulbs. High-sensitivity 
protection schemes that can improve protection against personnel 
shock are being investigated. A promising device for improving 
safety of diode- grounded dc machines is being evaluated. The de- 
vice responds to changes in dl/dt, reverse leakage current, ampli- 
tude, and deviations from preset values of ground current. 





TROLLEY LINE POWER : The incidence of mine fires caused by ground 
faults on trolley lines has prompted Bureau of Mines research into 
better circuit breakers, effective methods for isolating faulty 
sections, and an improved system for feeding power to locomotives 
through trolley wires. The Bureau's discriminating circuit break- 
er responds to short circuits, causing a fault current drain as 
small as 15 amperes while permitting the flow of legitimate load 
currents in the range of 3,500 amperes. At 150-ampere sensitivi- 
ty, the system can protect the line without requiring installation 
of onboard equipment on vehicles up to 30-ton draw bar pull size. 
An automatic energizing system was developed for little-used haul- 
age sections, operated by an oscillator onboard the vehicle. At 
MSHA's request, portable hardware was developed by the Bureau for 
online calibration of direct-current circuit breakers. 



73 



REMOTE CONTROL CIRCUIT BREAKER FOR TROLLEY LINES : Movement of 
off-track mining equipment in an entry with an energized trolley 
line is a hazardous operation. Section 75.1003-2 of the Code of 
Federal Regulations defines elaborate precautions that must be 
taken during such moves; however, in spite of these precautions, 
serious hazards still exist. The contact of the equipment and the 
trolley line can easily cause equipment damage, mine fires, or 
electrocution; standard circuit breakers do not have the sophisti- 
cation, speed, or accuracy to appreciably reduce these hazards. 
The Bureau has developed a system that overcomes these deficien- 
cies. This system, which can be interfaced to standard circuit 
breakers, permits the locomotive operator to select the minimum 
current needed to operate the locomotive, to break and remake the 
circuit, and to communicate. This system based on fail-safe prin- 
ciples, will automatically trip the circuit breaker if contact is 
made with the line and minimum current is exceeded, or a failure 
occurs anywhere in the system. 





GROUNDING : A good grounding system is paramount 
tion of equipment and personnel in a mine or min 
facility. The Bureau's research has contributed 
MSHA's and the mining industry's understanding an 
the importance of good grounding systems. Researc 
ed to the development of acceptable ground check 
lines, understanding of hazardous step and touch 
portance of proper selection of materials for grou 
tion and many other aspects of this vital safety 
denced by the picture, much of this better u 
grounding principles was communicated via workshop 
ized hands-on instruction. 



for the protec- 
erals processing 
significantly to 
d acceptance of 
h has contribut- 
monitor guide- 
potentials, im- 
nd bed construc- 
area. As evi- 
nderstanding of 
s and personal- 



74 



HIGH-VOLTAGE PROXIMITY WARNING DEVICES : The necessity for mobile 
cranes to work in the vicinity of overhead power lines frequently 
results in severe hazards, jeopardizing the safety of the equip- 
ment operator and nearby personnel. Present Federal Regulations 
(CFR, Title 30, Parts 77.807-2 and 77.807-3) specify that equip- 
ment of this nature should not be operated within 10 feet, or more, 
depending on the line voltage of an energized power line. As an 
aid to avoiding equipment contact with energized power lines, sev- 
eral warning devices are marketed that are designed to detect 
proximity of equipment extensions to overhead power lines and pro- 
vide both a visible and audible warning to the operator. Three 
electrostatic field sensing proximity warning devices were tested 
using full-scale cranes and power line systems, a scaled model 
facility, environmental testing facilities, and theoretical /numer- 
ical analysis. 





MINERALS PROCESSING PLANTS: 



operations, and coal 
to accomplish their 
has concentrated on 
Electrical Code to 



Dredges, smelters, crushing and 
preparation plants all require elec- 
beneficiation process. Past Bureau 
assessing the applicability of the 
these types of facilities, deter- 
of safe electrical practices and guidelines, and investi- 
of special electrical problems. For example, is the 
in the photo effectively grounded because it is 
Or, should it be remotely grounded from a con- 
located on the shore? Research has shown 
resistivities (similar to earth), and these 



grinding 

tricity 

research 

National 

mi nation 

gat ions 

dredge shown 

floating in water? 

ventional ground bed 



that water has varying 
questions can only be answered after measurements are made. Re- 
search will continue to assess potential electrical hazards and 
methods of protecting mining personnel from them. The safety of 
older mill electrical systems will be investigated to determine 
any potential safety hazards, as well as the cost/benefit of up- 
grading the facilities. 



75 



DESIGNS AND CRITERIA FOR CANOPIES : To assist mine operators in 
complying with MSHA regulations on protective cabs and canopies, a 
number of Bureau contracts were let. Canopies were designed and 
installed on mining equipment used in mines with coal seam heights 
ranging from more than 48 inches down to less than 36 inches, like 
the lowcoal vehicle shown. Protective cab and canopy designs were 
an integral part of the Bureau's Inherently Safe Mining Systems 
project demonstrated at the Jenny and Pawnee No. 10 Mines. New 
and unique canopy designs that have been developed include a 
three-support post design for improved visibility; modularized 
compartments that maximize operator comfort and visibility and are 
vertically adjustable as a complete unit; cantilevered and adjust- 
able sections for maximum room and comfort; and floating skid 
decks to provide a rigid platform for the operator to ride. It is 
estimated that spinoffs from Bureau research account for 20 per- 
cent of the total canopy designs now being used. 





PROTECTIVE STRUCTURES FOR LOW COAL FACE EQUIPMENT: Roof falls 
continue to be the major cause of fatalities in underground coal 
mines, with face equipment operators suffering more deaths than 
all underground workers. Lack of protective structure technology 
for low coal applications is evident, as MSHA has rescinded cab 
and canopy requirements for equipment operating in seams below 42 
inches. To develop this technology, the Bureau, through various 
contractors, has designed a range of low coal cabs for various 
face equipment. Pictured is a mockup fabrication of a transver- 
sely mounted floating cab for a shuttle car. Mockup fabrication 
of the canopy concept has been found to be an extremely useful 
portion of the overall design procedure. It allows problems in 
the design to be corrected at low cost before the actual compart- 
ment is constructed, and is useful in establishing the effective- 
ness of human factors design criteria. 



76 



DESIGN OF NEW RAILROAD TRUCK ASSEMBLIES : The Coal Mine Health and 
Safety Act of 1969, Public Law 91-173, specifies that underground 
rail vehicles be equipped with automatic brakes. In response, the 
Bureau has sponsored a study of accidents involving underground 
rail transport, and an evaluation of the economic cost/benefit 
ratio resulting from an industry-wide use of automatic brakes. 
Because of the high degree of variability between car designs, a 
single retrofittable package is not possible; and furthermore, the 
frequency of accidents that could be classed as "brake prevent- 
able" was exceedingly low. These two facts, very high unit cost 
and a low accident rate, resulted in an unfavorable projected cost 
ratio of 100 to 1. Thus, $100 would have to be expended to real- 
ize $1 in accident reduction benefits. Further negating the advis- 
ability of implementing brakes is the steadily declining popula- 
tion of underground rail cars. 




Area of visibility 
improvement 




IMPROVED VISIBILITY SYSTEMS FOR LARGE HAULAGE TRUCKS : As haulage 
trucks become larger, the field- of- view of drivers decreases be- 
cause of the position of the cab and obstructions on the rad- 
iator deck, and as a result, collisions in open pit mines have in- 
creased over the last few years. To help solve this problem, the 
Bureau has developed prototype visibility systems that consist of 
right-and left-hand mirrors, and fresnel lens "blind area viewers" 
to improve the driver's field of vision. The prototype system was 
on- vehicle tested at- Kaiser Steel's Eagle Mountain Mine. The blind 
area viewers cost approximately $750 each, and the mirrors, about 
$500. A second generation system is undergoing long-term, in-mine 
testing at the Erie Mining Co. Mine in Minnesota for cold weather 
evaluation, at Kaiser Steel's Eagle Moutain Mine for hot weather 
evaluation, and at the Decker Mine in Montana for surface coal 
mine evaluation. Commercial production of the fresnel lens blind 
area viewer is in process. 



77 



EQUIPMENT SAFETY ANALYSIS : Although safety features are best in- 
corporated when equipment is under development, safety often is 
deferred when competing with cost and performance. Techniques 
have been developed by the aerospace industry to evaluate and com- 
pare the safety of even complex systems, and these techniques are 
being successfully applied to mining systems. The safety of two 
complex systems, the Blind Shaft Borer and the Impactor Shaft 
Sinker, is being evaluated concurrent with the design and testing 
of their prototypes. Quantitative assessments are justifying the 
system designs and operating procedures. Knowledge gained through 
these two projects is being used to formulate techniques for eval- 
uating and improving the safety of commercial systems through the 
use of computers. 





CONVEYING : Transporting coal near and away from the face with 
shuttle cars and conveyors exposes the miner to danger. This 
results from shuttle cars moving back and forth with poor operator 
visibility and within a narrow area. A pneumatic haulage system 
has been designed for low coal and multiple entries that would 
eliminate the moving shuttle car and would provide more open space 
for the miners behind the mining machine. Even when using a pneu- 
matic conveying system, belt conveyors would still be used for 
long-distance haulage underground. Miner accidents associated 
with conveyors usually occur while the conveyors are being in- 
stalled, moved, or maintained. New tools and procedures are being 
developed to reduce these hazards, and belt conveyor designs are 
being studied that would be more reliable and easier to install 
and move. 



78 



IMPROVED HAULAGE TRUCK LADDERS: 



Statistics have shown that about 



37 percent of all off-road, hauler- related, lost-time injuries are 
attributed to slips and falls. The major hazard areas are exces- 
sively flexible lower steps or rungs, inappropriate lower step 
height, poor ladder design, and inadequate handrail and guardrail 
designs. Additional hazards are introduced by the lack of proper 
maintenance of ladders and the operators practice of carrying 
articles onto the truck. A Bureau contractor has developed and 
demonstrated several improved ladder designs. The most effective 
design, the four-spring supported lower step, rigidly supports an 
average operator yet flexes freely when it comes in contact with a 
berm or rock, thus minimizing maintenance. For easier accessibil- 
ity, the bottom step height has also been lowered to within 2 feet 
from ground level. The new design is currently undergoing long- 
term testing in five operating mines. 



Rigid ladder 
ssembly 




Hi-grip step 
material (typical) 



Pretension spring 
assembly (typical) 




ROPS PERFORMANCE CRITERIA FOR MINING EQUIPMENT : The use of ROPS 
(Roll Over Protective Systems) has shown that fatalities are sig- 
nificantly reduced when ROPS-equipped surface mining equipment is 
used. Since the development of ROPS is still in its infancy, 
little is known of its durability. Surface mining equipment 
equipped with ROPS is continually subjected to vibrations inherent 
to the equipment on which they are mounted. Ductile materials 
subjected to cyclic stresses, such as vibration, much lower than 
their static fracture strength, can fatigue, reducing the effec- 
tiveness of ROPS. Since MSHA safety standards reference the SAE 
performance criteria for ROPS, it is imperative that the perfor- 
mance criteria be established for mobile mining equipment that 
weighs more than 132,000 pounds. The Bureau is evaluating current 
ROPS systems in the field. 



71 



BELT DRESSING APPLICATOR : MSHA accident analyses have shown that 
conventional aerosol or swab application of belt dressing have 
resulted in at least four fatal accidents and a number of dis- 
abling injuries, primarily because workers' limbs were exposed to 
pinch-points of the conveyor belt head pulley and housing. To 
eliminate that hazard, different application techniques have been 
explored by the Bureau to permit belt dressing to be applied with- 
out worker exposure to moving belts, and the need to crawl into 
areas where material falling from a moving conveyor could cause 
injury. The best Bureau-developed technique (photo) uses a port- 
able garden sprayer, whose extended spray range makes it more 
suitable than spray from an aerosol can. Moreover, the safer tech- 
nique is cheaper; liquid belt dressing in bulk form costs approxi- 
mately one-third that in aerosol cans. Field tests have confirmed 
that the garden sprayer technique enhances the safe and economic 
application of mine conveyor belt dressing. 





AIR-LINE LINKING COMPONENTS : Except when automatic shut off de- 
vices are used, MSHA regulations (Health and Safety Standard 
57.13-21) require a secondary positive locking, securing, or re- 
straining device at each 3/4-inch-diameter or larger, high- 
pressure hose connection. These devices are designed to protect 
workmen against violent whipping of the hose in case of a high- 
pressure connection failure. However, it has been difficult to 
evaluate the effectiveness of the devices because of insufficient 
data on the force exerted by such a whipping action. The force 
generated in 1/2-to 6- inch-diameter hoses operating under 80-to 
120-psig has been determined, and the resulting information is 
being used by MSHA to develop performance standards for secondary 
restraining devices and regulations governing the installation of 
high-pressure air lines. 



80 



ILLUMINATION STANDARDS DEVELOPMENT: 



The main thrust of the Bu- 



reau's current illumination research in metal /nonmetal mines is to 
undertake basic studies to provide MSHA with guidelines for estab- 
lishing illumination standards. The Bureau is conducting visits 
to 10 mines including copper, trona, lead and zinc, and uranium 
mines throughout the United States. At each mine a team will 
observe a dozen or more work sites and 50 or more separate unit 
operations and collect mineral and rock samples for testing at the 
contractor's mine illumination laboratory. A goniophotometer is 
used to measure reflectance values of the samples in the labor- 
atory. This study will attempt to determine the minimum luminance 
requirements of the various worksites and visual tasks, and pro- 
vide the basic psychophysical data for the formulation of illumi- 
nation standards. 




■ ■ ■ ' I I L 



I I I I I I I I I I I 



20 , . . 10 
Z, feet 



INTERACTIVE COMPUTER SYSTEM FOR EVALUATING MINE ILLUMINATION: 
The Bureau of Mines has developed a computer program for calcula- 
ting the illumination on coal mine surfaces due to machine-mounted 
lights. Utilizing numerical models of mining machinery and mea- 
sured data on luminaire output characteristics, the program 
computes the foot-candle levels incident on the mine entry sur- 
faces for any desired machine/luminai re/entry configuration. 
Shadowing effects of the machine are taken into account. Results 
are provided at 2-foot intervals on the face, left and right 
walls, floor an.d roof. The program operates interactively from 
a graphics terminal and has been installed on a computer that com- 
municates with the terminal via telephone line. This computer 
program will allow MSHA to rapidly analyze proposed mining machine 
lighting configurations without resorting to the time-consuming 
method of building physical mockups and manually taking light 
intensity readings. 



81 



UNDERGROUND ILLUMINATION— HARDWARE : In an effort to improve on 
the mainstay of underground coal mine illumination, the miner's 
cap lamp. Bureau work has led to the successful development of 
several prototype nickel cadmium batteries. Estimated reductions 
of 50 percent in weight and 24 percent in volume are possible with 
this new design without any stored energy reduction. A compatible 
charging system has also been designed and tested. 




Ill 




DC POWER SUPPLIES : The Bureau has developed a solid state power 
supply and ballasting system capable of handling a mix of lamp 
loads up to 650 watts from 300-or 600-volt trolley wires. A com- 
plete lighting system consisting of a 600-volt to 300-volt conver- 
ter unit, a 300-volt inverter unit with ballasts, and two, 100- 
watt mercury vapor headlamps and six, 75-watt fluorescent lamps 
was tested at Republic Steel's Banning coal mine. The system op- 
erated for over a year without servicing. 



82 



UNDERGROUND ILLUMINATION— BASIC STUDIES: 



A current stu 



taken by the Bureau involves the development of guideline 
stallation and maintenance of mine illumination systems, 
termination of the state-of-the-art, and the identifi 
problem areas warranting further research and development 
with seam heights varying from 36 to 108 inches are bei 
ed. In-depth interviews are being conducted with lighti 
facturers. This study will aid in preparing a handbook 
lines and procedures for the industry to use in reducin 
nance problems, repair costs, and downtime caused by 
systems. 



dy under- 
s for in- 
the de- 
cation of 
Mines 
ng visit- 
ng manu- 
of guide- 
g mainte- 
lighting 





UNDERGROUND ILLUMINATION— HIGH SEAM COAL MINING MACHINERY : The 
first successful demonstration of an illumination system on a high 
seam diesel powered mining machine was performed by the Bureau. 
It involved the integration of a permissible lighting system into 
a thick seam diesel powered roof drill. The roof drill, operating 
in a 12-foot seam of Westmoreland Coal Co. Orchard Valley Mine, 
was modified with an integrated generator, eight, 64-watt fluores- 
cents, and two, 70-watt high-pressure sodium headlamps. A roof 
bolter of the same model is currently available, complete with an 
MSHA- approved illumination system. 



83 



UNDERGROUND ILLUMINATION— MEDIUM SEAM 
continuous miner was integrated with 



COAL MINING MACHINERY : A 

a permissible lighting system 

(7-foot seam). National Mine 

5012N miner using two, 70-watt 



at Consol's Westland No. 2 Mine 
Service has modified a Marietta 
high-pressure sodium headlights and four, 65-watt fluorescent 
lights. The lighting system was designed using a wooden mockup 
miner in a dark room at the MSHA Academy in Beckley, W. Va. Dur- 
ing 1,714 hours of machine operation in the mine, only 7 hours of 
downtime was caused by the lights, proving the reliability of the 
system. This equipment is now available with illumination pack- 
ages installed. 





UNDERGROUND ILLUMINATION--THIN SEAM COAL MINING MACHINERY : In the 
Bureau's effort to prove the feasibility of lighting to ^the stan- 
dard mining machines of all types and sizes, a permissible light- 
ing system was integrated into a thin seam roof drill and face 
drill. The roof drill in Lady Jane Collieries Mine (38-inch seam) 
was illuminated with five, IBO-watt high pressure sodium lamps. 
In 1,218 hours of operating time, only 15 minutes of downtime was 
due to the lighting system failure. The system was favorably 
accepted. The E. & K. Coal Co.'s face drill was illuminated with 
two, 100-watt mercury vapor and four, 150-watt high pressure sodium 
lamps. This system was satisfactorily accepted by the operators. 



84 



UNDERGROUND ILLUMINATION— SHORTWALL MINING: 



Due to renewed inter- 
in shortwall mining, the Bureau has demonstrated the feasibil- 
of the new lighting regulations (CFR, Title 30, Parts 75.1719 
■4) in an underground shortwall mining section. 



est 
ity 

through 75.1719- 

The Helen Mining Co.'s 200-ft shortwall section was used, which 
incorporated 40 Westfalia chocks in conjunction with a remote- 
controlled continuous miner. The section was illuminated to com- 
pliance levels using 44 fluorescent lamps, (1,500 ma each), one on 
each chock except for the first and last which had three. The 
system met with favorable response and proved itself mineworthy. 





METAL/NONMETAL DEMONSTRATIONS: 



The demonstration of coal mine 



illumination technology in room-and-pil lar metal /nonmetal mines 
was successfully undertaken by the Bureau. Two illumination 
systems were designed, installed, and evaluated on two continuous 
mining machines located in an underground trona mine in Wyoming. 
One used a fluorescent system and the other a high pressure sodium 
system. The most desirable system consisted of two, 70-watt high- 
pressure sodium lamps and two, 150-watt incandescent headlights. 
The luminaires were retrofitted on the machine with minimum amount 
of effort and proved to be very mineworthy, operating maintenance 
free for over 2,200 hours (almost 1 year). This demonstration has 
encouraged other mines with similar type operations to illuminate 
their machines. 



85 



SURFACE ILLUMINATION— DIESEL EQUIPMENT : In an effort to demon- 
strate the feasibility of illuminating large diesel- powered sur- 
face mining equipment to the proposed standards. Bureau research 
is focusing on using high-intensity discharge (H.I.D.) lamps to 
meet the standards and improve general area lighting. However, 
the illumination of diesel-powered equipment using H.I.D. lamps 
presents special problems, mainly the limited power available from 
the 24-volt battery on these machines. Therefore, the Bureau has 
developed solid-state power supplies and ballasts capable of pow- 
ering the H.I.D. lamps using the 24-volt battery found standard 
on these machines. 





UNDERGROUND ILLUMINATION— KEEP-ALIVE MERCURY MINE LIGHTING SYSTEM : 
In an attempt to provide better illumination in underground coal 
mines, new and better luminaires are continuously being intro- 
duced for use on underground coal mining machinery, 
is the high intensity discharge mercury vapor lamp, 
with these lamps however, is that they extinguish 
line voltage at the machine temporarily sags or is 
It then takes several minutes for the lamps to cool 
will restart. To solve this problem an auxiliary high frequency 
supply has been developed which provides additional power to the 
lamps automatically when they are in danger of extinguishing. 
These supplies are each capable of handling up to six, 175-watt 
mercury vapor lamps and two, 100-watt flood lamps. 



One of these 

The problem 

whenever the 

interrupted. 

before they 



86 



SURFACE ILLUMINATION— LARGE DRAGLINES AND SHOVELS : An evaluation 

and demonstration of the benefits of adequate illumination systems 

on large draglines and stripping shovels was done under a Bureau 

contract. The Delta and Leahy Mines of Amax Coal Co. 

sites of the 60-and 176-cubic yard draglines and the 

yard shovel which were illuminated. The illumination 

the 176-cubic yard dragline consisted of eleven, 

pressure sodium lamps, while the other two machines 

1 ,000-watt high-pressure sodium lamps, nine on the 

dragline and eight on the 105-cubic yard shovel. 

worked fine, but did not include lighting of the 

ways. To meet the minimum 

foot-candles in these areas would 

basic study to reevaluate minimum 

ior walkways, using a visual task 



are the 
105-cubic 
system on 
400-watt high- 
were lit with 
176-cubic yard 
These systems 
exterior walk- 
luminance requirements of 5- 
require 300 luminaires. Thus, a 
luminance requirements of exter- 
evaluator, has been initiated. 





UHF RADIO-TO-UNDERGROUND VEHICLES WITHOUT LEAKY FEEDER CABLES : 
UHF (ultra high frequency) is a practical way to achieve two- w ay 
communications in underground mines. Small personal and vehicu- 
lar radios are commercially available. However, for long- 
distance communication, it is necessary to install a special 
"leaky feeder" cable that must be run into the operational areas 
of the mine, which is often an impractical and expensive proposi- 
tion. Bureau research has shown that if the mine entries are 
large enough, the signals can be beamed down the main entryways 
and reflected into secondary entryways via roof-mounted passive 
reflectors. This concept is being evaluated in a large room and 
pillar limestone mine. Communication is possible between large 
ore haulage trucks and a central station. Because there are no 
"leaky feeder" cables to install or maintain, operation is more 
reliable and minewide. 



87 



IMPROVED RAIL HAULAGE COMMUNICATIONS : Communications with moving 
tracked vehicles in a rail haulage mine is a difficult problem, 
since communication usually takes place from a dispatcher to a 
vehicle, or from vehicle-to-vehicle on the trolley line, a very 
poor communications line. With the advent of larger mines, larger 
locomotives, and larger rectifiers to power them, the communica- 
tion problem gets worse. Dead spots, fading, noise, etc., occur 
all along the line and have an impact on operations and safety. 
The Bureau has investigated these problems and has tested tech- 
niques to minimize them. These are based in part on the use of 
dedicated wires, low impedance lines, and load isolation. Guide- 
lines were developed and are available to the mining industry to 
solve this problem. Included in the guidelines are details on how 
to improve the performance of equipment such as the carrier phone 
mounted on a mine locomotive. 





MANUAL FOR MINE COMMUNICATIONS, CONTROL, AND MONITORING : A vast 
amount of Bureau research has been done over the years in mine 
communications, control, and monitoring. Generally the results of 
this research are in the form of highly technical engineering re- 
ports useful only to researchers and engineers. A 
gather, reduce, and present this information in a 
able form for mine managers, mining engineers, 
engineers, who must specify, purchase, maintain, 
shoot the systems. As a result, a manual was prepared that can be 
updated as new technologies and techniques develop. The manual 
describes the characteristics of standard pager phones (pictured), 
carrier phones, hoist phones, radio systems, and monitoring and 
control equipment. 



need existed to 
readily avail- 

and electrical 
and trouble- 



88 



VISUAL PAGING SYSTEMS : One of the most difficult problems in the 
underground environment is contacting roving personnel. Because 
they often can be anywhere underground, considerable time is lost 
in locating these people, a situation that has an effect on opera- 
tions, safety, and production. Radio paging has been evaluated 
underground with good results. In this scheme, a small pocket re- 
ceiver is activated if it is within range of a radio signal. But 
even this is often not adequate. An alternative is visual paging 
where visual indicators are "set" in key areas of the mine. These 
visual indicators are usually numbers or letters that are assigned 
to various personnel. The visual signal, once "set", stays set 
until reset from the central station. When the person desired 
sees his signal set on any of the displays, he knows he is being 
paged, and contacts the central station for instructions. 





^HBSmipi 



« « I 




SELECTABLE PAGER PHONE : Loudspeaking pager phones are the most 
popular form of communications in underground mines. They are in- 
expensive and reliable, and general compatibility exists between 
those manufactured by different companies. However, because they 
are party-line systems, there is no way to selectively page from 
one phone to another or to leave a message on a particular phone 
if it was called but not answered. The Bureau has designed a 
small circuit that overcomes these deficiencies and is com- 
patible with all existing pager phones as an add-on. In opera- 
tion, a phone can be selectively called from any other phone. A 
beep-back signal assures the user that the desired phone has been 
accessed. If the called phone is not answered, a small indicating 
light flashes until the phone is picked up, or a predetermined 
time period has elapsed. Thus, the system offers selective paging, 
supervisory feedback, and message holding on the called phone. 



89 



UNDERGROUND TELEPHONE SYSTEM : At the Sunshine Mine in Idaho, the 
Bureau is demonstrating how the special communication needs of 
deep hardrock mines can be met with presently available communica- 
tions equipment. The party line magneto telephone system origin- 
ally in use at this 6,000-foot deep silver mine has proved in- 
adequate for both operational and emergency situations. The new 
telephone system allows private conversations with selective dial- 
ing to over 40 telephones, distributed underground and in surface 
facilities. An automatic telephone exchange located 4,000 feet 
underground and a subscriber carrier system permit the use of a 
single pair of wires to interconnect all telephones. In case of 
power failure, the system can operate for several days on an emer- 
gency power supply. The telephone wires are shared by a super- 
visory system that monitors and controls the ventilation fans, 
pumps, and fire doors. The system has continued to operate reli- 
ably for several years and has provided valuable information for 
further research in this area. 





ENVIRONMENTAL MINE MONITORING SYSTEMS: 



Continuous mine monitor- 



ing systems have the potential for reducing hazards underground 
through early detection and warning of hazardous conditions, while 
at the same time increasing production by monitoring and con- 
trolling critical mine parameters. Such monitoring systems con- 
sist of sensors (fire detection, air quality, and air quantity), 
strategically located throughout the mine coupled to a central 
control station. The Bureau has several ongoing projects that in- 
clude hardware design, testing, and evaluation, and a systems en- 
gineering analysis of mine monitoring systems. In the hardware 
area, a commercially available monitoring system will be installed 
at the Lucerne and Black River Mines for observation and testing 
and at the Bruceton Mine for demonstration and experimentation. 



90 



HOISTING : Hoisting in mines has a 
the request of MSHA, research and 
hoists covered the following area 
hoists; (2) wire rope criteria; and 
tenance and inspection. Several cont 
of reports giving technical guidance 
tion, and maintenance of hoisting eq 
valuable source for future investi 
obvious hazard areas in which little 
Currently, the information is used 
standards for coal as well as noncoa 



high disaster potential. At 
development relating to mine 
s: (1) safety catches for 
(3) guidelines for hoist main- 
racts have generated a series 

for the selection, installa- 
uipment. They also provide a 
gat ions because they pinpoint 

or no research has been done, 
by MSHA in the enforcement of 
1 mines. 





HOIST SYSTEMS— GUIDELINES FOR COMPONENT SELECTION; 



The Bureau of 






Mines has initiated this project to develop comprehensive guide- 
lines for hoist system design. The first phase is a state- 
of-the-art world literature survey to extract criteria already in 
use for design and construction guide-lines. The second phase 
will obtain information from principal manufacturers of hoist 
equipment, recognized consultants in each area of concern, and 
mine operators of selected sites. From data guidelines, stand- 
ards, and criteria relative to design and analysis of new and used 
hoists will be developed. These guidelines will also be applied 
to the repair and maintenance of major components and will provide 
mine operators with information helpful in selecting hoist equip- 
ment suitable for the purpose intended and certifiable by MSHA for 
safety during operation. 



91 



DEVELOPMENT OF CONSISTENT LOW-G ARRESTMENT : 
Mines contract a program for testing, dev 
the behavior of arrestment devices for pe 
is being conducted. A test facility was 
performance of a personnel -carrying hoist 
mine shaft. One of the problem areas bei 
facility is the measurement and control of 
that occur during free fall on wood guides 
work, an adjustable wood dog and shock ab 
developed to decrease the shock of su 
Another approach to developing low-g arres 
incorporate energy absorbing devices on 
hoist, instead of relying on wood removal 
ical studies have shown this approach to be 



Under a Bureau of 
eloping, and analyzing 
rsonnel -carrying hoists 

built to simulate the 

during free fall in a 
ng studied at the test 

high transient forces 

As a reuslt of this 

sorber system is being 

dden fall engagement. 

tment technology is to 

the personnel-carrying 
or friction. Theoret- 

feasible. 





AND OVERLOAD ROPE PROTECTION SYSTEM FOR MINE HOISTS: Hoists 



SLACK 

used in deep underground mine shafts must operate 
heavy loading and hostile environment; a potential 
the conveyance may lodge against its guides while 



safely despite 
problem is that 
moving, causing 



A system to monitor the rope 
these unsafe conditions was 
system operates on the prin- 
force can be calculated by 
the rope tension at the cage 



a slack or overload rope condition, 
tension continuously so as to prevent 
designed under Bureau contract. The 
ciple that the unknown obstruction 
taking the scaled difference between 

(measured by a load cell) and the acceleration of the cage. When 
this difference exceeds a specified value, an alarm is signaled 
and corrective action may be taken. Additional sensors for hoist 
drum speed and cage chair position provide additional data for the 
signal processor. The signal processor records statistics of 
hoist operation, displays key parameters, and activates an alarm 
in case of a hazardous condition. A prototype will be constructed 
and tested in a mine. 



92 



WIRE ROPE TESTING : At the Pittsburgh Research Center, the Bureau 
is erecting a 9,600-square-foot Wire Rope Testing Laboratory that 
will contain a 750,000-pound horizontal axial fatigue and tensile 
testing machine with instrumentation and recording equipment to 
record breaking strength and stress-strain characteristics; a 
10,000-pound vertical tensile testing machine to test individual 
wires and record their strength; and a fatigue machine instrumen- 
ted to measure loads, elongation, stress-strain and to evaluate 
non-destructive test (NOT) devices. Prepared samples with varying 
degrees of degradation will be destructively tested to determine 
their remaining strength, which will be compared with strengths of 
samples from the original rope. Additional support for the facil- 
ity is being provided by contract work to investigate the effects 
of the metallurgical properties of rope. 





SYSTEM FOR HANDLING SUPPLIES IN UNDERGR OUND COAL MINES; 
gram was undertaken to design, build. 



A pro- 
system for 
A 



and evaluate a 
handling supplies in underground coal mines to reduce injuries, 
system based on palletization and mechanical handling of materials 
underground has been developed, in which a mechanical handling ve- 
hicle is used to unload pallets from the supply cars at the sec- 
tion and distribute them to various locations close to end use. 
The use of a battery-operated, permissible, low-profile forklift 
appears to be the most suitable for handling the supply pallets 
and could also be useful during equipment maintenance. This 
system is expected to reduce accidents by about 23 percent in the 
mine selected for program demonstration, while increasing produc- 
tivity by an estimated 3 percent. Currently, a study is being 
made to evaluate the industrywide acceptance potential of the new 
system. 



93 



HAULROAD BERM, GUARDRAIL AND SIGN STUDY AND DEMONSTRATION : The 
91 ant size of haulage trucks is causing problems with runaways 
runoffs, and with road grades, braking, turn radius, and berm con- 
struction. A new. Bureau-sponsored project will determine how to 
control runaway or runoffs of any size haulage vehicle. The feas- 
ibility of the various constraint concepts is being examined. A 
limited amount of full-scale field testing will be compared with 
computer simulation. Correlation of test results for small full- 
size haulage vehicles will establish the validity of the computer 
program and allow extrapolation of these data to the larger haul- 
age vehicles. Project results will help MSHA and mine operators 
design better restraint systems. A report will be prepared on a 
study that was conducted on signs for mine haul roads. 




94 



- DISASTER PREVENTION-- "^; 



Fire and Explosion Preventio 



Explosiv 

Methane Control .- 

Postdisaster, SurvivaU'||n^ \Y' 
Mi ne "Rescue *. .^* .M. . . ..\. 



Fire and Explosion Prevention 



1 ' 



'iP, 









The FIRE AND EXPLOSION PREVENTION PROGRAM is aimed 
at developing better methods of preventing, sup- 
pressing, and extinguishing fires and explosions in 
coal mines. Bureau research in metal /nonmetal 
mines has been directed primarily to combustibles 
transported into the mines, that is, timber, mine 
machinery, plastics, fuels, and lubricants, and to 
studies of timber fire propagation and fireproofing 
treatments for wood. The Bureau, in conjunction 
with industry, has developed fire protection sys- 
tems that sense the heat of a fire, warn of the 
hazard, automatically extinguish the fire, and shut 
down the engine. Over 4,000 commercially available 
systems have been installed on mining equipment. 

Some innovative techniques in fire research have 
resulted in Bureau-developed guidelines for detect- 
ing spontaneous combustion of coals during their 
mining, transportation, and storage; guidelines for 
construction of explosion-proof bulkheads and 
seals; a computer code for predicting pertinent 
conditions in the airways of a mine during normal 
operations and during emergency mine fire situa- 
tions. 



Major Problem Areas 

• Explosive gas mixtures 

• Explosioir propagation 
• Fri[cti oij^j i gni ti on : 

'ion 



ilniHsliU 



t Timber fires 
- Venti'lation disrupting 
forces 



iroaches 

"^■*^ L 

DetectflonJ 
jEliminatio 

sources ' 
• Explosive^ 
i Explosij|;;|y. 
i JFi re cf"^ 



♦*• 



To provide further insight into the technical 
aspects of fires and explosions, several test 
facilities are available for research. Recently, a 
multiple-entry section of the Bureau's Experimental 
Mine was converted to a fire test facility to 
permit simulation of a sealed fire in a mine gob or 
passageway. Still under construction is the Lake 
Lynn Laboratory, a composite facility that will be 
available for simulating both room-and-pillar and 
longwall workings for experimental fire and explo- 
sion research in a number of areas. 



96 



SPONTANEOUS COMBUSTION OF COAL; 



Laboratory-scale tests were 



desiqned to define the spontaneous combustion susceptibility of 
American coals and to develop chemical and thermal criteria for 
predicting or detecting the hazard in a mine. Data are now 
available to characterize the gas emissions, self-heatinq tempera- 
tures, and ignition temperatures of a wide range of lignite, 
subbituminous, and bituminous coals. These data have shown that 
the spontaneous combustion hazard is greatest with coal of high 
oxygen (>15 wt-pct) and low methane content (low-rank coals), and 
where the coals have been dried and subsequently exposed to moist 
air. Such coals have high oxygen absorption rates and can self- 
heat at ambient temperature, this research has provided improved 
guidelines for detecting spontaneous combustion of coals (photo) 
during their mining, transportation, and storage, and for develop- 
ing protective measures. 





I(,e to^Qi ion 
current 



Flow stroightener 

Ijd froction of , 
total particle^ 
current =^ 



PNEUMATIC FIRE DETECTION : Pneumatic, multitube gas analysis 
systems, originally designed for the detection of spontaneous 
combustion, are being modified for use as general fire protection 
systems for conveyor belt haulageways. The modified system will 
use the Bureau-developed submicrometer particle detector shown 
here and will have a faster sequencing time of about 20 seconds/ 
point. The initial system is to be tested at the Plateau Mine 
near Price, Utah. The adaptation of the pneumatic sampling meth- 
odology to the problem of fire detection is the result of continu- 
ing in-house research efforts to implement improved detectors and 
detection systems in underground mines. This type of system 
conforms to MSHA's recommendations for conveyor belt fire protec- 
tion systems and is expected to be a viable, cost-effective alter- 
native to systems presently in use. 



97 



DETECTOR EQUIVALENCY IN VENTILATED PASSAGEWAY FIRES : The data on 
conveyor belt fires obtained by MSHA was combined with the Bu- 
reau's data from the Bruceton mine fires, to develop a realistic 
model for the growth of fires in a ventilated passageway. The 
figure shown contrasts the severe requirements for thermal sensors 
(in the range of less than one foot) with the more reasonable 
requirements for product of combustion sensors (in the range of 
several hundred feet). The data also show that thermal sensor 
specifications for room enclosure fires are not applicable to 
ventilated passageways and generally give inadequate protection. 
Only continuous thermal sensors with low alarm thresholds are 
realistic. By contrast, CO sensors such as those tested by MSHA 
in conveyor belt haulageways give adequate protection at spacings 
of hundreds of meters. 



800 



700 

E 

u> 
z 
o 600 

CO 

q: 

8 500 

z 

LiJ 
CO 

g 400 

H 
i/> 

Zl 

m 



300- 



,z 



Quadratic fire growth 



/ 



/ 



/ 



X 



r 



Exponential fire growth 



0.25 0.50 0.75 1.0 1.5 

AIRFLOW, m/sec 




KEY 
Vertical sholr 



— AirwOy 

/g\ Junciion 



Surfoce juncTKXi 
LonqwQil face 
Direction of upward slope 
at kxigwoll face 



MINE (FIRE) VENTILATION COMPUTER CODE : A computer code for mine 
ventilation flow calculations, developed under Bureau contract, is 
capable of predicting ventilation flow rate, contaminant concen- 
tration, temperature, and pressure in each airway of a mine during 
normal operation as well as during emergency fire situations. The 
computer code is useful not only in estimating the normal flow 
conditions for ventilation design purposes, but also for identi- 
fying safe airways for escape and rescue measures in the event of 
a fire. Maximum capabilities of the computer code ave (1) number 
of airways, 200; (2) number of junctions, 150; and (3) number of 
fans, 20. Currently this ventilation computer code is being used 
by government agencies, mining industry, and universities. A 
video graphics system is being designed that will display the mine 
environment prior to and during a fire of a mine network. 



98 



FRICTIONAL IGNITION : Frictional ignition with quartzitic and 
pyritic materials is a well recognized hazard in the coal mining 
industry. MSHA reports have indicated a disturbing increase of 
frictional ignitions during the past several years; the frequency 
rate in 1979 was more than twice that in 1978. The major cause of 
frictional ignitions in coal mines is due to the cutting bits of 
mining machines; bits are especially hazardous if they are worn or 
broken and scrape against, instead of cutting into the material. 
For example, full-scale tests with a chisel -type bit cutting into 
sandstone have indicated that a bit worn only one-eighth of an 
inch easily ignites while a bit worn only one-thirty-second of an 
inch ignites with difficulty. Furthermore, the ignition hazard is 
reduced when a water spray is added to impact the cut surface 
directly in back of the bit, as shown here. 



•4^>XKi**€ 





SELECTIVE SUBMICROKETER PARTICULATE DETECTION : All products of 
combustion fire detectors tested thus far in noncoal mines invari- 
ably false alarm in the presence of diesel exhaust emissions. The 
selective submicrometer particulate detector shown here was devel- 
oped under a Bureau of Mines contract to discriminate between 
diesel and mine fire particulates. All particulates are repyro- 
lyzed and recondensed before they are detected. An important 
finding was that diesel exhaust particulates do not repyrolyze 
significantly, as do real fire particulates that form a large 
quantity of smaller particles. Thus, measuring the ratio of 
repyrolyzed to initial particulates allows the detection of real 
fire particulates in the presence of a large diesel particulate 
background. This instrument is now being evaluated in a real mine 
environment at the Black River Limestone Mine in Butler, Ky. 



99 



INCOMBUSTIBLE REQUIREMENTS : The mining industry requested the 
Bureau to update its early work on rock dust requirements, with 
the idea that low-volatile coal might be mined safely with less 
than the required 65 percent rock dust. Full-scale experiments 
were conducted in the Bruceton Experimental Mine with various 
concentrations of rock dust to coal dust from the Pocahontas, 
Sewell, and Pittsburgh seams. Observations on explosions like the 
one shown here indicated that slightly less rock dust is necessary 
to quench explosions in low volatile coal, but that this effect is 
minor compared with the effects of variations in strength of 
initiation and dust particle size. Consequently, the Bureau 
recommended against a change in regulations. In conjunction with 
this research, a quantitative treatment along the lines of flamma- 
bility limit theory was developed for rock dust inerting; the 65 
percent incombustible content that was an empirical value is now 
the basis for inerting. 





IGNITION QUENCHING DEVICE : Because the number of methane igni- 
tions reported annually appear to be increasing (nearly 100 igni- 
tions reported in 1979), the development of suitable extinguishing 
devices has continuing high priority. Initial efforts to retrofit 
existing continuous miners with ignition quenching units were 
technically successful but impractical because of the large number 
of units (up to 9) needed on each mining machine. Meanwhile, 
improved extinguishing agents have been developed that diffuse 
more readily around obstacles, thus reducing the weight of extin- 
guishant required and hardware dimensions. Water spray systems 
either integrated into existing dust suppression hardware or 
applied directly at the coal cutting bits also show considerable 
promise in eliminating the problem of frictional face ignitions. 
Initial tests with the back-mounted spray system shown here appear 
to reduce the likelihood of frictional ignitions. 



100 



EXPLOSION-PROOF SEALS : In response to the 1969 Coal Mine Health 
and Safety Act requirement that abandoned areas of a coal mine be 
either ventilated or sealed with "explosion-proof" bulkheads, 
research was undertaken to develop guidelines for construction of 



Bulkheads made of gypsum, fly-ash cement, and con- 
were subjected to explosion pressures up to 65 pounds 
inch, generated by methane-air and by coal dust-air 
Based on these experiments, preliminary specifica- 
tions were submitted and promulgated as Subsection 75-329-2 of the 
Code of Federal Regulations in November 1970. A detailed discus- 
explosion-proof bulkheads submitted in a memorandum to 
September 1971 was the basis of a draft of proposed rule- 
Alt hough not yet promulgated, the September 1971 memoran- 
used to advise operators on seal construction. Upon re- 



such seals. 
Crete block 
per square 
explosions. 



si on of 
MS HA in 
making, 
dum is 



quest, the Bureau tests the validity 
submitted to MSHA for approval. 



of novel bulkhead designs 





SEALED MINE FIRES : Once a coal mine area has been sealed follow- 
ing a fire, the problem then exists as to when and under what 
conditions the area can be opened without the risk of a reignition 
or explosion. To study such problems, the Bureau converted a 
multiple entry section of its Experimental Mine to a fire test 
facility that permits simulation of a sealed fire in a mine gob or 
passageway (photo). The test facility is instrumented with flow, 
pressure, temperature, and gas sampling probes in the fire zone 
and throughout the multiple entry. Data are continuously trans- 
mitted to a remote instrument control center equipped with data 
acquisition/recording instrumentation and a video system. Simula- 
ted mine gob fires in the facility have shown that the oxygen 
concentration decreases exponentially with time after sealing and 
that the explosion or reignition hazard can be safely predicted if 
reliable data is obtained. 



101 



PARTICULATE DETECTION IN A SEALED FIRE AREA : Once a mine fire has 
been sealed, the possibility of reignitions or explosions must be 
ascertained before initiating rescue or recovery operations. The 
data shown were obtained in a simulated, sealed, coal gob fire in 
the Bruceton Experimental Mine. The concentration of submicron 
particulates, measured with the Bureau's patented detector, de- 
creases by three orders of magnitude as the temperature of an 11- 
ton coal -pile fire cools during the 2 weeks after sealing. By 
contrast, the CO concentration levels off and becomes insensitive 
to the coal temperature. Thus, particulate measurements provide a 
more realistic measure of fire extinction conditions than can be 
obtained from CO or other gas composition measurements. Such data 
can answer the question of when it is safe to reopen and recover a 
mine that has been sealed because of an uncontrollable fire. 



o 
t- 
<; 

(X 



LU 
O 



< 
O 
O 



1 1 1 1 1 


1 


o 


>^ 


Particle data °/^ 




~(Ln(particles/cnn')) . ° y^ 




y^O 


~ 


y^ 


Time of ~ 


y^ ° ^COdata {Ln (ppm)) 


sealing 


- 


\ 
\ 


f - 


-* Time 

1 1 1 1 1 


\ 



100 200 300 400 500 600 700 800 

TEMPERATURE, °C 




REMOTE SEALING OF MINE FIRES : A sealing system for remotely 
isolating or extinguishing underground coal mine fires has been 
developed. It includes sonar and closed circuit modules for 
probing a mine passageway, a fly-ash deployment unit for construc- 
ting the main seal, a froth foam unit for providing airtight 
closures, acoustical equipment for monitoring seal completion, and 
a generator for inerting the sealed passageway. This remote 
procedure avoids exposure of firefighters to toxic and/or explo- 
sive atmospheres, eliminates sealing the entire mine, and expe- 
dites mine recovery. It was used to successfully isolate an 
underground fire in Eastern Associated Coal Corp.'s Joanne Mine, 
and in fighting the Bethlehem Steel Mine fire at Ebensberg, Pa. 
The complete system was successfuly demonstrated at the Bureau's 
Jenny Mine complex in the fall of 1978, and is now part of MSHA's 
emergency response capability. 



102 



FIRE AND EXPLOSION HAZARDS OF OIL SHALE MINING AND PROCESSING : The 
Bureau's research program Tn this field iTas been expanded to 
include dust explosion and rubble fire tests in the Experimental 
Mine, sampling of dust, and monitoring of scattered fires in and 
around mines by a contractor, and a cooperative project with a 
mine operator to monitor methane emissions in an active oil shale 
mine. In the latter project, the Bureau's tube bundle monitoring 
system, formerly used on coal mine fires, has been moved to the 
site and adapted to monitor methane and other gases in the mine 
continuously as mining proceeds. In the mine explosion tests, 
data show that fine oil shale dust (minus 200-mesh) will propagate 
flame when the volatile content is above 50 grams per cubic meter. 
The laboratory and field studies are providing MSHA with the data 
needed to develop improved safety guidelines for oil shale mining. 





ACCIDENT ANALYSIS FOR MSHA : Following major fires and explosions, 
the Bureau makes research facilities and personnel available in 
support of MSHA recovery operations. Thus, after the Scotia Mine 
disaster in 1976, explosions were conducted in the Bruceton Exper- 
imental Mine to test a layered-methane scenario, and a small-scale 
model of two passageways in the mine was constructed to test the 
investigators' conclusions as to the point of initiation of the 
second explosion. In general, as soon as boreholes can be opened 
into a sealed disaster area, the Bureau provides an instrumenta- 
tion trailer with various gas analyzers, such as those shown here. 
This monitoring capability helped facilitate the recovery opera- 
tions in the Scotia Mine disaster, and it is currently being used 
to evaluate any gas explosion hazard in an oil shale mine at Horse 
Draw, Colo. 



103 



FIRE RESISTANCE TEST METHO D FOR CONVEYOR BELTS; 

TCFR" 



The 
requires 



Code 
that 



of 
all 



Federal Regulations CCFR~ Title 30, Part T5) 
conveyor belts in underground coal mines be fire resistant and 
meet the acceptance criteria of the Part 18 fire test method. To 
meet the small-scale limitations of the method, a moderate-scale 
apparatus was designed to operate under burning conditions that 
represent a realistic mine fire situation. The apparatus, which 
accommodates belt samples up to 46cm wide and 152cm long, is 
designed to burn the samples in a horizontal attitude (photo), 
and is equipped with a ribbon flame ignition source, a radiant 
panel for preheating the belt and instrumentation for monitoring 
intensity and extent of propagation. The method is sufficiently 
sensitive to discriminate between belts of low, moderate, and high 
fire resistance and provides a more reliable measure for predic- 
ting conveyor belt fire hazards in a mine than is possible by 
other laboratory-scale test methods. 




f\ 





IMPROVED FIRE-RESISTANT HYDRAULIC FLUIDS : Fire-resistant hydrau- 
lic fluids, as approved by MSHA's Federal Schedule 30, are re- 
quired to be used on coal mining machines that ^r^ unattended or 
those that ^iVQ attended but not protected by a fire suppression 
system. Under a cost-sharing contract, an improved inert emulsion 
hydraulic fluid was developed that has satisfactory functional 
properties and contains at least 43 wt-pct water plus a flame 
retardant to overcome the fire resistance limitations of existing 
The fluid was successfully demonstrated in a 1-year 
mine test on two continuous mining machines equipped 
and gear type pumps. In addition, fluid design and 
criteria were def'ined and a novel field test kit 
developed to permit rapid and reliable determination 
of the water content, viscosity, and contamination of the fluid at 
the mine site. 



products, 
underground 
with piston 
performance 
(photo) was 



104 



UNDERGROUND MOBILE EQUIPMENT FIRE PROTECTION : Manually activated, 
fixed piping fire protection systems have been used on underground 
vehicles for the last few years. Such systems have extinguished 
numerous fires, but experience has shown that in a fast-developing 
fire, such as a burst hydraulic line, the driver abandons the 
vehicle before activating the fire system and/or shutting down the 
engine. A number of deaths have been attritDuted to this growing 
hazard. To help solve this problem, the Bureau has developed an 
in-mine, on-vehicle, fire-tested, automatic fire protection system 
for mobile mining equipment. The system senses the heat of a fire 
and warns the driver of the hazard. Then, if the driver does not 
manually activate the system, the system automatically extin- 
guishes the fire with dry chemical and shuts down the engine. 
Second generation hardware is being long-term, endurance tested in 
the Bunker Hill Mine, and Morton Salt's Grand Saline Mine. 





Electric*! Cabrnett Thermal S«nior 
Warnrng Horn 

Manual OiicharK* Control 
Control Box 



Lubricant Storage Thermal Seni 



FIRE PROTECTION FOR LARGE, ENCLOSED, SURFACE MINING EQUIPMENT : 
Draglines, loading shovels, and blasthole drills present complex 
fire protection problems. The optimum fire protection system 
design for this equipment requires the use of both Halon 1301 and 
dry chemical extinguishing agents. Complete automatic fire sen- 
sing and suppression systems, which employ both Halon 1301 and dry 
chemical, have been developed and in-mine tested by the Bureau on 
a 170-cubic-yard dragline, an 8-yard loading shovel, and two, 15- 
inch-diameter blasthole drills. These systems feature visual and 
audible warnings in case of fire, automatic machine shutdown, and 

fire control systems. Three of the 
harsh mining environment for over 2- 



automatic actuation of the 
systems have operated in a 
1/2 years. This advanced 



Motor - Generator Set Thermal Seme 



fire protection technology has been 
transferred to the private sector; systems patterned after Bureau- 
developed designs are now available from three commercial sources. 



105 



MOBILE SURFACE MINING EQUIPMENT FIRE PROTECTION : Fires on mobile 
surface mining equipment are a serious hazard to life and proper- 
ty. The Bureau of Mines, through contract and in-house research, 
has developed and demonstrated reasonably priced, reliable auto- 
matic fire protection systems. Systems suitable for use on haul- 
age trucks, front-end loaders, dozers, hydraulic excavators, and 
other mobile equipment were designed, fabricated, bench tested, 
and installed on operating mine equipment. Second- and third- 
generation prototypes have operated in the mining environment 



without failure for over 24 months, 
automatic systems patterned after the 
and more than 4,000 units are now in 
technical input from the Bureau, the 



Five firms are marketing 
Bureau-developed designs, 
use in mines. Utilizing 
National Fire Protection 



Association is preparing 
mine mobile equipment. 



a National Fire Code covering surface 




Ex1lnquis^er shells 
with pressurizing 
gos cortridges 




IMPROVED METHANE MONITORS : New and improved methane monitors have 
been developed for electric face equipment in compliance with 
CFR, Title 30, Part 75.313, and Section 303(e) of the 1969 Act, 
resulting in significantly improved production monitors that 
feature an aspirated sampling head or a replaceable precalibrated 
head for reliability and accurately sampling the face air. Power 
supplies that withstand mine power voltage fluctuations and 
provide battery for monitor operation with machine power off have 
been demonstrated. An infrared methane monitor has been developed 
that has successfully demonstrated calibration-free performance in 
Consolidation Coal's Ireland Mine and has also spun off into a 
successful CO2 diesel vehicle monitor. These devices will reduce 
production loss and/or unsafe practices caused by mine equipment 
shutdown due to methane monitor malfunctions. 



106 



ANEMOMETER CALIBRATION FACILITY: Section 303(b) of 1969 Coal Mine 
Health and Safety Act and CKR, Title 30, Part 75.301 requires 
accurate determination of air flows or ventilation quantities in 
underground mines. This in turn requires anemometers that are 
accurate at flows below 100 feet per minute (fpm). Until late 
1975 there was no facility in the United States capable of check- 
ing anemometer performance or calibration below 200 fpm. At the 
request of MSHA, a low-velocity anemometer calibration facility 
was developed at the National Bureau of Standards, Gaithersburg, 
Md. This facility is now operational and, with Bureau funding, is 
providing standard reference anemometers calibrated over their 
full operating range. With these references, MSHA can establish 
secondary standards and secondary calibration sources in district 
offices. The NBS calibration service is also available to commer- 
cial users and suppliers of air velocity measuring devices. 





REMOTE DUST DEPOSITION METER : Because a surface layer of float 
coal dust that is only 0.1 mm thick (8 mg/cm^) can propagate an 
explosion in a codl mine, close monitoring of the deposition of 
coal dust and . ' inerting rock dust is obviously required to 
assess the explosion risk. To improve this capability, the Bureau 
funded the development of a remote dust deposition meter system, 
in which deposition sensors placed in the returns and elsewhere 
are wired to a remote station where a readout meter measures the 
mass of the dust deposits on the sensors. The deposition sensor 
consists of a thin metal diaphragm whose resonant frequency is 
measured; the mass of the deposit is obtained from the change in 
resonant frequency as the diaphragm is loaded with dust. When the 
coal dust deposit reaches a hazardous level (ca 5 mg/cm2), rock 
dust must be applied, or similarly, when 20 mg/m^ of rock dust has 
been deposited, sufficient rock dust has been deposited to meet 
the 80 percent requirement in the return. The initial prototype 
hardware is undergoing field evaluation. 



107 



SCANNING ELECTRON MICROSCOPE (SEM) STUDIES OF DUSTS : Basic struc- 
tural information on coal and oil shale dusts and their mixtures 
with explosion inhibitors provide valuable information on the 
mechanism of flame propagation and inhibition. The Bureau's SEM 
is capable of obtaining micrographSo at magnifications of 50,000, 
at resolving pov/ers better than 300A, and is equipped with an X- 
ray detector for simultaneous elemental microanalysis. In addi- 
tion to basic studies of dust combustion, data may provide a more 
sound scientific basis for post disaster investigations. The 
photo shown is a micrograph of a coal dust/KHC03 mixture. 




Inhibitor 


Incombustible Required to Inert, Percent 


8-Liter 
Chamber 


2-Meter Diameter 
Gallery 


Experimental Mine 


KHCO3 

(Purple-K) 

CaC03 

(Rock Dust) 

KCl 

(Super K) 

NaC1 
(BCD) 

NH4H2PO4 


70 
60 
55 
50 
26 


70 - 75 
65 - 70 
25 - 35 
20 - 30 
15-25 


70 
67 - 72 
10 - 45 
40 - 45 
25 - 30 



DUST FLAMMABILITY STUDIES : The applicability of small-scale flam- 
mability tests to full-scale mine explosions has frequently been 
questioned. One chemical inhibitor. Purple K (KHCO3), which was 
effective in some small-scale studies, proved to be even less 
effective than rock dust in full-scale mine tests. Some research- 
ers had despaired of ever finding an effective chemical inhibitor 
against coal dust explosions. The data shown here indicates that 
the new. Bureau-developed, 8-liter flammability chamber gives 
reliable data for all the cases thus far studied. Inhibitor 
effectiveness data for this laboratory-scale system are in good 
agreement with full-scale tests. Ammonium phosphates are very 
effective "chemical" inhibitors and other classes of effective 
extinguishants have been discovered in recent laboratory studies. 
Reliable laboratory-scale studies are cost-effective screening 
tests for full-scale mine experiments. 



108 



FIRE HAZARDS OF MINE TIMBERS : A large-scale fire gallery (a T- 
shaped structure with two, 150-foot-long and 8-foot-square pass- 
ageways), developed and operated under a Bureau contract, has been 
used to test and evaluate the following fire safety measures for 
metal /nonmetal mines: maximum untreated and f ire-retardant treat- 
ed timber loading densities in a passageway to avoid fire spread; 
relative fire hazards of untreated and treated timbers, and small 
(6- by 6-inch) and large (12- by 12-inch) timber sets; fire haz- 
ards of spilled liquid fuels in a passageway; fire endurance of 
wooden bulkheads, and fire resistance of untreated and treated 
conveyor belts. Some of these measures have been proposed for 
fire safety regulations; for example, a maximum untreated timber 
loading density of 30 percent for underground fire hazard areas. 
Effects of slopes on timber fires are being investigated. 




- V 

C-LEVEL ^-\ 



FIRE TEST ZONE 









11071 1 
A -LEVEL 1 


RAISE 




TO SURFACE ,JV 


>/.< 


* 100 




< 


n ^^° 


w 


2^ 
< < 


» SCO 






^> 700 














ca cd ^°° 








^ 




-FIRE TEST 
ZONE 






1300 


1100 










r 








1500 




TO SURFACE .j^ 












9200 


W 








9000 






6800 1 


) SURFACE 




6500 1 




8300 
61 OO 


TC 



SHAFT FIRE AND SMOKE PROTECTION : At the request of MSHA, the 
Bureau has developed a fire and smoke protection system designed 
for use in mine shafts. Sensors capable of detecting smoke, 
carbon monoxide, and high temperatures are installed at one or 
more shaft stations where their signals multiplex to a surface 
control unit. In case of fire, this unit remotely closes smoke- 
control doors at the fire level and activates remotely controlled 
extinguish the fire. The surface control unit also 
electronics to minimize wiring cost. The cost of 
unit and protection of one level is esti- 
costs for additional levels ranging 
successfully demonstrated 



sprinklers to 

uses multiple 

the surface control 

mated at about $100,000, with 

from $10,000 to $30,000. The system was 



at the 3,000-foot level in the 
levels in the Pine Creek Mine. 



Silver Summit Mine and at two 



109 



UNDERGROUND FUELING AREA FIRE PROTECTION SYSTEMS : As mines modern- 
ize, the refueling and fuel storage areas of deep underground 
mines become increasingly dangerous with respect to fire hazards. 
Combustion products from a single barrel of oil could kill every- 
one in the mine before they had time to escape. In conjunction 
with MSHA and the National Fire Protection Association, the Bureau 
developed a low-cost (about $12,000) system that optically detects 
a fire in the fueling arediy then automatically extinguishes the 
fire, first with dry chemical to inhibit the fast developing fire 
and then, with an aqueous film-forming foam agent that cools the 
fire area for long-term extinguishment. A second generation 
system installed in AMAX's Buick lead and zinc mine near Boss, 
Mo., is currently undergoing long-term, reliability testing. A 
third, portable system will undergo in-mine testing at Allied 
Chemical's Green River trona mine near Green River, Wyo. 





IMPROVED UNDERGROUND METAL/NONMETAL FIRE PROTECTION HARDWARE : 
A number of fire protection system prototypes have been developed 
by the Bureau to meet the increasing hazard posed by deeper, 
hotter, and more mechanized mines. A shaft fire and smoke protec- 
tion system was developed, as well as a spontaneous combustion 
fire warning system for noncoal mines. A commercial version is 
now being tested at Diamond Crystal's Jefferson Island salt mine 
near New Iberia, La. The spontaneous combustion fire warning 
hardware was initially tested in Magma Copper Co.'s Superior Mine 
near Globe, Ariz., and a long-term test of this system's hardware 
is now underway. In-mine reliability testing of fire sensors is 
being conducted at the Lakeshore Copper Mine near Casa Grande, 
Ariz. The Becon smoke sensors have operated successfully for 
about 3 years — with jio maintenance, and the mine owner wants to 
expand the cooperative work in the next year. 



110 



TEST FACILITIES : Several underground test facilities are current- 
ly operated by the Bureau. The Safety Research Coal Mine and the 
Experimental Mine, located at Bruceton, Pa., are used, respective- 
ly* for general mine experiments and single- and double-entry 
fires and explosion research; the Lake Lynn Laboratory presently 
under construction in Fayette County, Pa., will be a composite 
facility made up of a single- and a triple-entry mine with inter- 
connecting passageways to the adjacent inactive limestone mine 
(see figure), making it possible to simulate both room-and-pillar 
and longwall workings for experimental purposes. The laboratory 
will be used to evaluate fire and explosion extinguishing devices 
and control techniques, passive and active explosion barriers, and 
ventilation stoppings and bulkheads. Investigations will provide 
information on flames from dust explosions, speed with which gas 
pressures build up in front of flames, composition of gases at 
various stages of explosions, and the explosibility limits of coal 
dust mixtures. 




Ill 







The Bureau's EXPLOSIVES RESEARCH PROGRAM 
is aimed at developing safer permissible 
explosives and detonators for use in 
mining; devising safer blasting tech- 
niques and methods for loading blast- 
holes, and developing methods for pre- 
dicting the range of "fly-rock" from 
surface blasting. The behavior of new 
explosives is continuously monitored, 
and new tests and standards are being 
developed to upgrade the safety and 
performance of permissible explosives. 

In a related area, MSHA frequently 
requests the Bureau to examine explo- 
sives allegedly involved in various 
accidents or illegal use. Responding to 
this need, the Bureau has developed a 
method of identifying ("tagging") explo- 
sives from their post-detonation resi- 
dues. As a result of this program, a 
nationwide program of explosive "tag- 
ging" is being considered to assist in 
detecting illegal use of explosives in 
terrorist bombings as well as those 
involved in mining accidents. 

Another interesting byproduct of the 
Explosives Research Program is a propo- 
sal by the United Nations Committee on 
Transport of Dangerous Goods for apply- 
ing Bureau-developed tests to the gener- 
al classification of explosive materials 
and articles. 



ALTERNATIVE TO KELLY BAR LOADING OF BLASTHOLES; 



When blastholes 



are drilled in wet, porous, unstable strata, they tend to fill 
with water, silt, or mud as soon as the drill is withdrawn, pre- 
venting the loading of explosives into the holes. Under these 
circumstances, the traditional method of loading explosives is to 
load the cartridges through the hollow drill steel (Kelly Bar), 
which often causes accidental detonations during attempts to 
dislodge explosives jammed in the Kelly Bar. A safer, more effi- 
cient method has been developed, in which durable but expendable 
hollow tubes of hot-wax-dipped or phenol ic-resin-treated paper- 
board are loaded through the Kelly Bar, and subsequently loaded 
with explosives after the drill is withdrawn. Both cartridged 
dynamite and (in larger diameter holes) bulk slurry explosives can 
be used. MSHA regulations in CFR, Title 30, Parts 55.6-142, 56.6- 
142, and 57.6-142, were based on this method. 




-Base charge 



-Acceptor train 



-Flyer plate 
"Donor charge 
-Delay train 
-Igniter chorge 
"Bridge wire 



-Antistatic coil 
-Antistatic chip 



-External legwires 



DEVELOPMENT OF SAFER DETONATORS : Prototype electric blasting 
caps (detonators) have been developed that have no primary explo- 
sive and are thus much less sensitive to initiation by an acciden- 
tal impact. For example, they could not be initiated by a 2.4- 
kilogram weight dropped from a height of 120 cm, while conven- 
tional detonators can be initiated by drops from heights of 15 to 
90 cm. The electric blasting caps are also less sensitive to 
detonation by high temperature than most commercial detonators, 
are far less sensitive to initiation by electrostatic energy, and 
stray electric current. In addition, the prototype detonators 
have a lower incendivity (tendency to ignite flammable atmo- 
spheres) than some of the detonators in use. Current efforts are 
aimed at improving the electrical comparability to conventional 
detonators so that the same firing-circuit parameters can be used. 
Arrangements are being made to transfer this technology after 
field testing. 



113 



EVALUATION OF ELECTRICAL STORM WARNING SYSTEMS 



; A small but 

caused by premature 

by lightning, that 

firing circuit acts 

energy from remote 

from a blasting 



significant number of blasting accidents are 
detonation of electrically initiated blasts 
does not need to strike directly, because the 
as an antenna that picks up electromagnetic 
lightning flashes. Failure to withdraw personnel 
area in time is due to the uncertainty of the distance at which a 
storm becomes dangerous, and to the fact that electrically charged 
clouds can build up quietly in the vicinity without warning. A 
field study of six basically different types of electrical storm 
warning systems under various weather and topographic conditions 
with simulated firing circuits showed that 10 miles is the minimum 
safe distance. Performance criteria for an electrical storm 
warning system were developed, and while none of the commercial 
systems tested were completely satisfactory, recommendations were 
made for improvement of system designs. 




10,000 



5,000 



-2,000 



o 1,000 
O 



500 - 





1 

/b = 4 


1 1 1 1 
b= minimum burden, feet 


" 


/ / 


/b = 8 y^ 

/b=l2 ^^ 
/ ^/b=l6 


- / 




/ X ^ ' 


// 


/ J / 


/ / /^=20 

/ /b=30 - 
< 1 /i 1 



6 10 14 

BOREHOLE DIAMETER, inches 



ESTIMATION OF MAXIMUM RANGE OF FLY-ROCK : One of the chief causes 
of accidents resulting from surface blasting is fly-rock that 
lands farther from the shot avea than expected, causing property 
damage or injuries. This is due partly to unexpected conditions 
in the rock being shot ("wild" fly-rock) and partly to lack of an 
accurate procedure for estimating the normal maximum fly-rock 
range, A mathematical technique has been developed, based on 
measurements of actual fly-rock ranges, for predicting the expect- 
ed fly-rock range from both vertical faces and bench tops, given 
the blast-hole diameter, spacing, powder factor, rock type, eleva- 
tion, and other parameters. Based on this procedure, nomographs 
for predicting fly-rock range were developed for use by blasters. 



114 



EXPLOSIVE IDENTIFICATION; 



The need to detect explosives used 
was amply demonstrated by a 1970 mine 



illegally in coal mines 
disaster in which the use of nonpermissible explosives was cited. 
In response to this need, a method of identifying explosives from 
their postdetonation residues has been developed. The explosives 
are "seeded" during manufacture with "tags" of colored-laminated 
polymer particles. The particles contain a fluorescent layer for 
identification under ultraviolet light, and a magnetic layer that 
separates from other debris by use of a magnet. Further, the 
fluorescent layer can be color coded to distinguish between per- 
missible and nonpermissible explosives. Microscopic observation 
of tag layer colors identifies the manufacturing plant, date 
produced, and batch number. The technique, successfully demon- 
strated in underground coal mines, can also be applied to identify 
explosives used in terrorist bombings. A nationwide program of 
explosive tagging is being considered by a Congressional committee. 




F3 
4 YELLOW 
2 RED 
8 GRAY 
6 BLUE 
1 BROWN 
9 WHITE 
3 ORANGE 




'/2~inch plywood . 
1/2 -inch sheetrock , 



\ '/4-inch plywood 

'/8~inch low-carbon steel 



BARRIERS AND CONTAINERS : Investigation of the adequacy of barriers 
between detonators and explosives when transported in the same 
vehicle, which are required and specified by MSHA standards, has 
shown that the construction standards specified are adequate to 
prevent sympathetic initiation of the explosive only for a limited 
number of detonators when the latter mass-detonate. A dynamite 
cartridge on one side of a 4-inch hardwood barrier detonated when 
100, No. 8 strength detonators with their downstream ends pointing 
toward the barrier were fired simultaneously, but not when 50 
detonators were used. An alternative composite construction, 
recommended by the Institute of Makers of Explosives, failed to 
prevent initiation by 25 detonators fired simultaneously, but 
prevented initiation when 12 detonators were used. The Bureau 
developed an alternate construction which successfully prevented 
sympathetic detonation by 100, No. 8 strength detonators fired 
simultaneously in worst-case-tests. 



115 



DEVELOPMENT OF SAFER PERMISSIBLE EXPLOSIVES : The Bureau's objec- 
tive is to maintain the safety of permissible explosives currently 
used in underground coal mines, and to improve those areas as 
necessary. Since the Bureau's introduction of the relatively safe 
permissible water-gel explosive approved for underground use in 
1970, twenty additional formulations have been approved. (Water 
gels now comprise about 35 percent of permissible explosives 
sales.) The Bureau continuously monitors new explosives, and 
develops new tests, standards, and schedules to improve their 
safety and performance. At MSHA's request the Bureau frequently 
examines explosives allegedly involved in 
incidents. The photograph shows a steel 
involved in a fatal explosion accident, 
explosive mixed with coal used for heating 



various accidents or 

drum used as a stove 

in which undetonated 

detonated during the 



burning of the coal in the drum, which was being used as a stove. 





in 



Electric detonator 

-Cardboard container 

Explosive test sample 
Lead cylinder 




Steel plate 

Wood block 



CLASSIFICATION OF HAZARDOUS MATERIALS : An integrated scheme for 
applying Bureau-developed tests to the general classification of 
explosive materials and articles has been proposed for adoption by 
the United Nations Committee on the Transport of Dangerous Goods. 
These tests will be performed by the Bureau for the U.S. Depart- 
ment of Transportation to define the hazard classification of 
explosive materials used in mining as well as other applications. 
MSHA regulations regarding explosives transportation, storage 
handling and use employ a distinction between "explosives" and 
"blasting agents". Whether an explosive substance is classified 
as an explosive or blasting agent depends primarily on the sensi- 
tivity of the material; in particular, if the material can be 
initiated to detonation by a number 8 detonator, it is classified 
as an explosive rather than a blasting agent. However, other 
types of tests which define the sensitivity of the material to 
heat, flame, shock and other mechanical stimuli are also consider- 
ed in the classification. 



116 




The METHANE CONTROL PROGRAM is developing the 
technologies necessary for safe and economic mining 
of methane-laden coalbeds. Technology to control 
methane in advance of mining is being developed, 
largely for application to virgin coal. Such 
techniques as water infusion, novel methods of face 
ventilation, and drainage through horizontal holes 
ahead of the face are being developed for methane 
control during mining. Some of the ventilation 
techniques for control of methane, funded under 
this program, are discussed in a separate subsec- 
tion on ventilation, for purposes of consolidation 
in this report. 

Operation of an underground pipeline with automatic 
safety controls is being demonstrated in the Pitts- 
burgh coal bed at the Marianna No. 58 Mine. More 
than 124 million cubic feet of methane has been 
pipelined to the surface, and other pipeline demon- 
strations are planned for the Mary Lee, Sunnyside, 
and Beckley coalbeds. If methane has not been 
drained from the coal before mining starts, water 
infusion can block the flow of methane to the 
working face. Demonstrations in the Upper Kittan- 
ning, Pittsburgh, and Sunnyside coalbeds have 
reduced methane flow rates from faces by 40 to 89 
percent. A novel method for sealing water infusion 
holes has been developed that reduces capital 
equipment costs significantly. 

The Bureau's Methane Control Program includes the 
determination of methane content of coalbeds to 
define areas where methane control problems can be 
anticipated. Procedures and equipment have been 
developed, and adopted by the mining industry, 
universities, and government agencies. 



117 



GEOLOGIC STUDIES TO EVALUATE THE GASSY NATURE OF COALBEDS: 



The 
geo- 



20 



methane content of coal beds depends upon rank, depth, and 
logical factors such as environment of deposition, cleat, meta- 
morphism, and coalbed discontinuities. To define areas in which 
methane control problems can be anticipated, the Bureau has 
conducted geologic studies for coalbeds that will be extensively 
mined in the near future, in Alabama, Colorado, Utah, Oklahoma, 
Pennsylvania, Virginia, and West Virginia. The resulting data 
are used to delineate high methane areas in the Mary Lee coalbed 
in Alabama, the Beckley coalbed in West Virginia, the Pittsburgh 
coalbed in Pennsylvania and West Virginia, the Freeport and Kit- 
tanning coalbeds in Pennsylvania, and the Hartshorne coalbed in 
Oklahoma. Graphs of increasing gas content with depth, like that 
for the Hartshorne coalbed shown here, can be used in conjunction 
with geologic maps to plan mine ventilation systems and assess 
methane drainage in advance of mining. 




500 1,000 

DEPTH, feet 



1,500 




PREDICTION OF COALBED DISCONTINUITIES: 



The presence of coalbed 
shown, as well as clay 



discontinuities such as the "rock spar 
veins, channel sandstones, and the other various types of "wants", 
can directly affect the drilling of vertical and horizontal 
methane drainage boreholes. Hitting a discontinuity with a 
borehole can severely limit its potential for methane drainage. 
Data obtained from a mathematical description of coalbed discon- 
tinuities developed from geologic studies in the Beckley coalbed, 
have been used to determine the probability of horizontal methane 
drainage boreholes of various lengths encountering discontinu- 
ities. Also, the number of vertical boreholes likely to encounter 
discontinuities at various spacings in a multiborehole pattern can 
be determined. Similar analysis can also be used by coal com- 
panies to determine the probability of advancing mains or sections 
encountering discontinuities and aid in the development of an 
exploration coring program. 



118 



DIRECT METHOD OF DET ERMINING THE GAS CONTENT OF COALBEDS; 

content 



To 



determine fHe gas content oT coalbeds, a simple, fnexpensive 
($100), field method was developed by the Bureau in which gas 
desorbed from a coal core is measured. Data obtained are used to 
delineate areas of high gas concentrations, to estimate ventila- 
tion requirements, and as the basis for research on the geologic 
factors that influence the occurrence of methane in coal measures. 
The Bureau, at the request of mining companies and various Federal 
and State agencies, determined the gas content of nearly 800 coal 
samples from 145 coalbeds in 15 states. This technique, known as 
the "direct" method, has recently been adopted by several major 
coal companies; federal agencies, universities, and several state 
geologic agencies trained by the Bureau are using the test in 
their coalbed research programs. 



Valve 
30 lb/in'' gage/fJN 




Pan of water 




METHANE DRAINAGE FROM VERTICAL BOREHOLES : Vertical methane drain- 
age boreholes, represented by the surface installation shown here, 
are used in areas where access to virgin gassy coalbeds is not 
possible underground. Near-mine vertical boreholes have particu- 

mining requirements provide insufficient 
degasification by the horizontal borehole 
Bureau has conducted methane control re- 
boreholes in 16 different coalbeds repre- 
major U.S. coal producing areas; draining 
feet of gas from coal. Gas drainage rates 
yielded more than 200,000 cubic feet per 
coalbed in Alabama and 100,000 cubic feet 
coalbed in Pennsylvania. It is note- 
in the gassy Mary Lee coalbed experi- 



lar application where 
lead-time for advance 
method. To date, the 
search using vertical 
senting nearly all the 
nearly a billion cubic 
after stimulation have 
day from the Mary Lee 
per day from the Pittsburgh 
worthy that a mine operating 
enced a 40-percent reduction in methane emissions while developing 
in an area previously degasified using only two vertical bore- 
holes. 



119 



METHANE HYDRAULIC STIMULATION TECHNIQUES : Methane gas production 
from vertical boreholes is normally limited because of the inher- 
ent low permeability of coal. To increase gas flow, hydraulic 
stimulation techniques adapted by the Bureau from oil -field tech- 
nology are utilized to widen and extend the naturally occurring 
coalbed fracture system. During the stimulation process, sand- 
laden fluid injected under pressure 
extension and propagations of sand 
highly conducive to gas and water flow, 
has not been shown to change the structural integrity of associ- 
ated roof strata. Hydraulic stimulation directly affects critical 
elements of the vertical borehole degasification process. The 
area of coalbed water drainage and pressure reduction is normally 
increased from tens to hundreds of feet; moreover, prestimulation 
production rates have been increased by 500 percent after hydrau- 
lic stimulation. 



into the coalbed, causes 

filled pathways, that are 

, The stimulation procedure 




\ Feb 6-7. 1975 


'A July 15. 1975' 1 ' 1 


— r 


1 ' 


1 1 


\Maf. 11.1975 


-J \ aOcI 30. 1975 






- 


Apr 25. 1976 


June 5, 1975^./ \ 










fluq 28. 1975 \ 

\ Oec 10, 1975 

H ^on. 13, 1976 








- 






- 


- 


\A 


4 


1976 

June 9, 1976 




^ 


Feb 12, 1976 3>^ \ 


V. 


y^June 23, 1976 


- 


_ 


Apr a. 1976' 




\ 


_ 


1 


1 




Aug 25, 1976 t^ 

1 1 


■*Sepl t6, I976_ 

1 1 



3.000 2.500 2,000 1.500 1.000 

DISTANCE BETWEEN COAL FACE AND HONEY RUN SHAFT, fl 



METHANE DRAINAGE THROUGH SHAFTS : The Bureau has demonstrated that 
large quantities of methane can be obtained through horizontal 
holes drilled into virgin coal from the base of air shafts, 3 to 
5 years in advance of need for ventilation. Drained gas is calor- 
ifically and compositional ly equivalent to natural gas and can be 
sold to recover the costs of drainage. At Federal No. 2 Mine, 
seven horizontal drainage holes were drilled from the base of a 
14-foot-diameter shaft and produced 1.2 billion cubic feet of gas 
in 7.5 years. At the same mine, five horizontal drainage holes 
drilled from the base of an 18-foot-diameter air shaft produced 
882 million cubic feet of gas in 3.7 years. When mine entries 
were driven through the degasified area, methane emission at the 
face declined 70 percent, as shown in the figure. Some of the gas 
was sold to Consolidated Natural Gas Co. This simple, practical 
degasification method will soon be applied at the Beckley Mine in 
the Beckley coalbed and the North Mine in the Lower Kittanning 
coalbed. 



120 



GAS DRA INAGE 
drilled 



IN AN ADVANCING 
advance 



SECTION : Horizontal drainage holes 
ciTvert methane from the faces of 
Consequently, methane flows 
significantly, and machine 
concentrations higher than 
entirely. Generally, the 
be at least equal to the 



Gas flow 



in advance of a section 
the section to the holes, as shown, 
at face areas during mining are reduced 
stoppages due to detection of methane 
1 percent are reduced or eliminated 
length of the drainage holes should 

width of the section. After the section is advanced halfway 
along the drainage holes, the hole drilling phase is repeated. 
This degasification method has been integrated into the mining 
cycle by Consolidation Coal Co. and methane flows have been 
reduced by 50 percent in the immediate returns. Jim Walter 
Resources No. 4 Mine and Virginia Pocahontas No. 5 Mine in the 
Pocahontas No. 3 coalbed will soon be applying this degasifica- 
tion method. 





WATER INFUSION; 



ing 



Water infusion is an effective method for reduc- 

methane flows at face areas during mining. Water is pumped 



into the coalbed through horizontal holes drilled in advance of 
the face; the water blocks the flow of methane into the face area, 
eliminating ventilation problem and reducing ignition hazards. 
Horizontal water infusion holes are sealed with commercially 
available packers during infusion. Capital costs for packers are 
$79,000; however, a packer developed by the Bureau reduced the 
cost to $600. The Bureau-designed packer can be constructed in a 
machine shop from commercially available materials. The expend- 
able packer is filled with grout that seals a plastic pipe in the 
infusion hole. No hazards occur when intercepted by the mining 
machine. Water infusion was successfully demonstrated in the 
Pittsburgh, Sunnyside, and Upper Kittanning coal beds where methane 
flow rates from faces were reduced 40 to 89 percent. 



121 



DRILLING EQUIPMENT AND TECHNIQUES : Methane flows from horizontal 
holes are directly proportional to their length and range from 80- 
to 500-cubic feet per day per foot of hole length. Horizontal 
holes are routinely drilled to 1,000 feet and to 2,500 feet with 
difficulty. Procedures and equipment have been developed for this 
purpose and are commercially available. The drill assembly enters 
the coalbed through 21 feet of 4-inch-diameter steel pipe, which 
is grouted in the coalbed and connected to a gas-water and drill 
cutting separator. Drill cuttings and water drop to the bottom of 
the separator and gas is drawn off at the top and ducted to the 
underground pipeline, as shown here. U.S. Steel Corp., Island 
Creek Coal Co., Jim Walter Resources, and Consolidation Coal Co. 
have purchased long-hole drill equipment for degasification. 





ELECTRONIC SURVEYING FOR HORIZONTAL DRILLING; 



A horizontal hole 



must be surveyed to determine bit inclination every 20 feet during 
drilling to maintain correct hole trajectory and to prevent the 
hole from intercepting the roof or floor. Bit inclination meas- 
urements are made with a commercial surveying instrument that is 
placed in the drill pipe and pumped with water to the end of the 
hole. For holes drilled to 1,000 feet, the average time per 
survey is about 16 minutes and increases to 34 minutes when hole 
depth is 2,000 feet; consequently, more than 50 percent of the 
time is spent surveying. An electronic surveying instrument 
located behind the bit has been developed, and bit inclination 
measurements are telemetered through the drill pipe and displayed 
in less than 1 minute on a driller's console, shown here. The 
instrument reduces surveying time significantly, aids in maintain- 
ing more precise control over hole trajectory, and permits routine 
drilling to 3,000 feet. 



122 



GROUTING HORIZONTAL DRAINAGE HOLES : Mining into a drainage hole 
releases large quantities oT methane directly into the cutting 
head of a miner, and the enormous quantities of ventilation air 
required to dilute methane rapidly to below 1 percent are dif- 
ficult to obtain at active face areas. Consequently, drainage 
holes are sealed to avoid explosive methane-air mixtures when 
intercepted by the mining machine. A cement slurry consisting of 
cement, fly ash, and a friction reducer is pumped through a poly- 
vinyl chloride pipe,<lnd inserted to within a few feet of the back 
part of the hole. When the cement slurry returns through the 
annulus to the collar of the hole, pumping pressure is increased 
to 200 psi to assure that grout fills the hole. When horizontal 
drainage holes plugged in this way were mined through, no methane 
problems or other safety hazards occurred, thus providing the 
industry with a simple, inexpensive method of complying with MSHA 
requirements. 









•<rr-%^sfll 


■I^^^H 






a 




n 


^Mm 


P^" 


l' 


*" iiinjiUJj'- T^jm 








f 




B»j^---j>^ 




PLUGGING OIL AND GAS WELLS : In northern West Virginia and west- 
ern Pennsylvania approximately 50 wells have been plugged since 
1977 and 21 have been safely mined through. Sulfur hexafluoride 
(SF5), a tracer gas, is used to check the competency of the plug. 
Absence of SF5 in the mine air indicates that no gaseous hydro- 
carbons were leaked into mine workings when the wells were inter- 
sected by mining. The Bureau developed the plugging procedures 
that allow safe underground mining through wells and eliminate the 
Federal requirement of a 300-foot-diameter protective pillar 
around oil and gas wells that penetrate the coalbed. Elimination 
of "well pillars" conserves minable coal reserves, improves pro- 
ductivity, permits more extensive longwall mining, and simplifies 
mine ventilation. MSHA has reported that plugging of oil and gas 
wells safely eliminates the need for coal barriers around wells. 



123 



UNDERGROUND METHANE PIPELINES : Because 1,000-foot horizontal 
drainage holes in coal beds produce methane at rates ranging from 
80,000 to 500,000 cfd, an underground pipeline must be installed 
and connected to a vertical borehole to transport methane to the 
surface where it can be put into a commercial gas transmission 
line or used at the mine site. The first operating underground 
pipeline is a steel line located in Marianna No. 58 Mine, shown 
here. Subsequent installations are polyethelene pipelines, which 
are easier to install, corrosion resistant, less costly than 
steel pipelines, and require less labor to install. Polyethelene 
pipelines have been installed in Jim Walter Resources No. 4 Mine, 
Virginia Pocahontas No. 5 Mine, and Sunnyside No. 1 Mine, and one 
is planned for the Beckley Mine. Guidelines for installation, 
maintenance, and safe operation of underground pipelines have been 
developed by MSHA and the Bureau. 





Compressed 



Venturi 
/2-inpipe. meter 



valve— pi_^ Gas-water 

Overflow Vli .^22!£|. 
control-^ H ^^l^-^-z^ 




Control 
panel 



Air compressor 

llOvac, 1.05 cfm 

80 psig 



8-in main line to surface 



ELECTRONIC METHANE MONITORING OF UNDERGROUND PIPELINES : Each hori- 
zontal drainage hole is equipped with a spring-loaded pneumatic 
valve that is held open with compressed air. These pneumatic 
valves are controlled by methane sensors located in the entries 
containing the methane pipeline. If the pipeline is ruptured by a 
roof fall and the methane concentration in the entry exceeds 1 
percent methane, the sensors automatically close the pneumatic 
valves. The methanometer head is accurate and rugged enough to 
operate in the hostile environment of a return air entry from an 
active face. The system is now operating at Marianna No. 58 Mine, 
and other monitoring systems will be installed in the Beckley 
Mine, Beckley, W. Va. and Sunnyside No. 1 Mine in Utah. All 
components of the methane monitoring system are marketed commer- 
cially. 



124 



GOB DRAINAGE : The large volumes of methane that accumulate in gob 
areas frequently cause severe ventilation problems in bleeder 
entries. Gob degasification boreholes are drilled from the sur- 
face into the overburden in advance of mining to assist conven- 
tional ventilation in the bleeder entries. Gob holes reduce 
methane in the bleeder entries as much as 60 percent as shown. 
Island Creek Coal Co., Bethlehem Mines Corp., Eastern Associated 
Coal Corp., and Consolidation Coal Corp. are using the Bureau gob 
degasification technique. New methods of gob gas control are 
being developed because topography may prevent 
boreholes and surface right-of-way costs are 
Bethlehem Mine Corp.'s No. 33 Mine, holes will 
underground locations upward over the gob and 
drawn from the gob with a vacuum pump or exhaust 



drilling surface 

escalating. At 

be drilled from 

methane will be 

fan. 



2.500 



2.000 



1.500 



1,000 



500 



"I 1 1 \ 1 1 1 1 1 1 r 




KEY 
• Borehole 20 
^ Underground 



J I I L_J L 



20 21 22 23 24 25 26 27 28 29 30 I 



1 

SEPTEMBER 



OCTOBER 




METAL/NONMETAL MINE METHANE CONTROL : Recent accidents have rein- 
forced the potential hazard of methane accumulation in selected 
metal /nonmetal mines. One such area is the Louisiana Gulf Coast 
salt mines where preliminary geological evaluations have been 
conducted. Preliminary discussions and limited field observations 
were conducted at the Jefferson Island, Weeks Island, Cote Blanche 
and Belle Isle Mines. Salt samples have been collected and used 
for preliminary evaluation of a procedure to determine gas content 
of the samples. The samples showed at least trace amounts of 
hydrocarbon gas emitted during dissolution of the salt. Gas flows 
from exploration holes were measured and found to vary consider- 
ably. Preliminary evaluation of all available information thus 
far indicates a highly variable occurrence and emission of methane 



in domal salt mines. Work will 
analysis, gas analysis, geologic 
possible effects of gas migration 
ing formations, and the changes 
geology and geochemistry of the 
study of the geology and mining 
underway. 



continue with additional sample 
mapping, investigation of the 

from adjacent petroleum produc- 
in emissions with changes in 

formations. Additionally, the 

of western oil shale mines is 



125 



f»^lll^9^K^^jl^ 






^s«^»-<»# 



, Postdisaster, Sur^Wa\^ifi^J^Beiie 



The Bureau's POSTDISASTER SURVIVAL AND RESCUE 
RESEARCH PROGRAM seeks to enhance a miner's chances 
of surviving a mine disaster through improved 
emergency life support, communications, and rescue 
procedures. A life-sustaining atmosphere is an 
immediate necessity to a trapped miner; thus the 
most important survival element is an immediate 
oxygen supply. In this connection, several Bureau 
contractors are developing lightweight, self-con- 
tained breathing apparatus having a 60-minute 
oxygen supply. A combined short- and long-term 
duration breathing apparatus has also been devel- 
oped, and was awarded an IR-100 Award in 1980, 



Portable mine rescue shelters have been developed 
to serve as a refuge for the trapped miner in an 
emergency. New methods of locating and communica- 
ting with trapped miners have enhanced rescue 
procedures. The Bureau has developed an electro- 
magnetic system that can be used from the surface 
to establish a two-way communications link with the 
trapped miner underground. A large surface trans- 
mitter is powerful enough to send voice messages by 
radio directly through the earth. In 1979 the 
Bureau won an IR*100 Award for this innovation. 



Approaches 



• Ins,t^i#com(iiuni cations to • S( 
ali^mfners to evacuate bi 

• Communications with v • P< 
J^trapped miners— ^ • E' 

- '-^ation of trapped ai 

'' miners • S( 

• Rescue of trapped miners .t( 

• Protection of rescuers • Er 
t Speed and safety of t^Si 

rescue operations 

• Survi val of trapped 



• Self-contained escape 
breathing devices 

• Portable »3gfuge s||eMels 

• Electromagnetic llocalifn 
and Gommuni cations sys^ 

•.Seismic detecting and * 
Jo c at i ng sys terns , "^^ 

• EmergferP" 

i^spii;' 



' team protecti ve 



A variety of rescue probes have been developed for 
lowering through a borehole to detect any faint 
sound of activity underground, to permit two-way 
voice communication if contact is made, to provide 
visual communication via a television system, and 
to monitor and sample the mine atomsphere for toxic 
gases, smoke, fire, temperature, and oxygen defi- 
ciency. The Bureau developed a portable mine fire 
gas analyzer for use by rescue personnel . Three 
units were delivered to MSHA. 



126 



OXYGEN SELF-RESCUERS: 



A survey of coal mine disasters over the 

30 years indicates that 20 to 30 percent of the miners who 
could have been saved if they had been equipped with a self- 
breathing apparatus. Thus, the single most important 

a small , 



last 
died 

contained 

survival element centers around providing each miner with 
lightweight, belt-worn oxygen supply. Several Bureau in-house 
projects and contracts are focused on developing two types of 
self-contained breathing apparatus, and evaluating in-mine deploy- 
ment alternatives. The more advanced, commercially available 
KO2 units are based on a chemical reaction that removes moisture 
and CO2 from the exhaled breath and produces enough oxygen for 60 
minutes of respiratory protection in a toxic or oxygen deficient 
atmosphere. The second type of self-contained breathing appara- 
tus, a compressed oxygen self-rescuer, is presently in the proto- 
type stage. Researchers are using state-of-the-art space age 
materials to reduce the device to a belt-worn size. 





COMBINED LONG/SHORT DURATION SELF-RESCUE BREATHING APPARATUS : 
Legislation (CFR, TTtTe W] Part 75.1714) requires that under- 
ground coal miners will be protected by oxygen self-rescuers. 
Since the present self-rescuers provide protection against only 
carbon monoxide gas, there was a clear need for oxygen self-rescu- 
ers that are self-contained. In response to this need, the Bureau 
has developed a combined long/short duration breathing apparatus 
consisting of a 10-minute unit that can be worn by the miner, and 
a 1-hour cannister that can be stored and attached quickly and 
safely, as needed, to the short-duration unit without removing the 
self-rescuer. A prototype system has been approved by NIOSH. 
This apparatus received an IR'IOO Award in 1980. 



127 



LOW TEMPERATURE TESTING OF RESCUE BREATHING APPARATUS : Mine rescue 
personnel wear rescue breathing apparatus (RBA) that are approved 
for use by NIOSH and MSHA. Because these tests are typically done 
at room temperature with only one test performed at 32° F, and 
because lower usage temperatures are easily possible, an investi- 
gation was conducted. Three RBA's commonly used in mine rescue 
were subjected to tests in subfreezing environments. Volunteers 
from the U.S. Army Institute of Environmental Medicine performed 
work tasks in a variety of cold temperatures to study the opera- 
ting limits of these RBA's and the manner in which they failed. 
Although results confirmed that the RBA's should not be used below 
freezing, information gained may result in strengthened designs 
that will favor lower operating temperatures, such as has been 
done by one manufacturer. 





LIQUID COOLING GARMENT : A portable personal cooling system has 
been developed for mine rescue operations. The high temperatures 
often encountered by mine rescue teams during emergency situations 
may cause such severe physiological strain that rescue operations 
are greatly hindered. A portable cooling system was needed to 
increase the duration of the rescue mission in such a harsh envir- 
onment. This system was based on technology developed to provide 
thermal control for space-suited astronauts. A cool alcohol and 
water solution flows first from the belt-worn, battery-operated 
pump to the head of the wearer. Next the liquid flows to a vest, 
cooling the trunk of the wearer, then back to a heat sink in a 
closed loop. The total system with the head and vest garment 
weighs 11 pounds. This system has a cooling capacity of 100 
kilocalories and is commercially available. 



128 



TRAPPED MINER LOCATION SYSTEM : A series of in-house projects and 
contracts has developed two feasible systems for locating and 
communicating with miners trapped underground by mine disasters. 
The first system, based on electromagnetic technology, has now 
been tested at 94 mines located throughout the coal fields of the 
United States. It consists of a surface receiver-transmitter used 
by the rescue team to detect, locate, and communicate with the 
trapped miners. A small belt-worn device, carried by the miner 
underground and powered by the miner's cap lamp battery, transmits 
electromagnetic signals to the surface and receives voice messages 

responds to the voice messages by 
on to provide answers in a "yes" or 
illustrated in the photo, won an 



from the surface. The miner 
keying the transmitter off and 
"no" fashion. This system, 
IR-100 Award in 1979. 





SEISMIC LOCATION SYSTEM: 



The second system, an alternative to the 
System, is based on through-the-earth 
vibrations, and is now a part of MSHA 
In operation, a surface array of 



Trapped Miner Location 
transmission of seismic 
standby emergency equipment, 
geophones senses ground vibrations produced by a miner pounding on 
the mine roof and uses the processed signal to locate the miner. 
These signals penetrate the overburden and can be detected by the 
geophones. Computer analysis of the received signals permits the 
source of the signals, and hence the miner's position, to be 
calculated. The photo illustrates the operation of this system. 
Location accuracy varies with mine depth and overburden character- 
istics, but accuracies in the range of 50 feet have been demon- 
strated numerous times. The Bureau has continued research on this 
system to enhance system performance by applying computer tech- 
niques to signal recovery. 



129 



RESCUE PROBES : During rescue and recovery operations boreholes 
are often drilled to obtain information on conditions underground 
and to search for signs of survivors. The Bureau has developed a 
series of instruments for use in borehole probe operations. One 
of these, a rugged, two-v/ay intercom system for communicating 
down the borehole, has a sensitive microphone system to detect 
faint sounds, and also allows two-way voice communication if 
contact is made. Visual communication is provided by a low-light 
level television system. Surface support equipment consists of a 
truck-mounted winch, TV monitors, and taping equipment. Gas can 
be sampled remotely from the surface, and analysis then performed 
at the site. Final delivery of all systems has been made to MSHA. 





HOIST RADIO SYSTEM : When an emergency occurs in a deep mine, 
voice communications between the hoist operator and the cage are 
essential for rescue and recovery. Commercially available hoist 
communication systems that couple signals onto the hoist rope 
have, in general, proved to be unreliable, and lack the necessary 
range, which often can be many thousands of feet. The need for 
better hardware in such situations prompted the Bureau to develop 
an emergency hoist radio system. This system, consisting of 
battery-powered 52 KHz transceivers and efficient signal couplers, 
has an operating range of 10,000 feet. This system was turned 
over to MSHA's Mine Emergency Operations Team and is held in 
readiness for emergency use. A commercial supplier of hoist- 
communications gear has included some of the features of this 
system in its product line. 



130 



COAL MINE ESCAPE HOIST GUIDELINES : Guidelines for selection and 
evaluation of emergency escape systems have been developed, and 
criteria established for safe and reliable emergency hoist that 
can be economically constructed from commercially available hard- 
ware. This allows practical enforcement of the statutory provi- 
sion of CFR 75.1 704-1 (b) , which specifies that escape shafts more 
than 20 feet deep include elevators, hoists, cranes, or other such 
devices, which shall be equipped with cages and buckets. Guide- 
lines and basic design specifications have been developed that 
permit mine operators to select an economic and safe hoisting 
system. They provide Federal inspectors with the criteria that 
will guarantee that only safe and reliable escape hoist systems 
are approved and maintained throughout the life of the mine. The 
design specifications also enable manufacturers to develop a 
standardized machine to meet the requirements of the law and the 
needs of the mining industry. 





fSSS^ 



MINE FIRE GAS ANALYZER : At the request of MSHA, the Bureau has 
developed a portable mine- fire gas analyzer that measures carbon 
monoxide, oxygen, carbon dioxide, hydrogen, and methane gases, as 
well as total combustibles, in underground return airways during 
mine firefighting and sealing operations. The composition of the 
return air during a fire reveals the status of the fire and the 
effectiveness of the fighting techniques, and can indicate a 
potentially explosive situation. Analysis of the fire gases 
during sealing and reopening operations is especially critical. 
The two-person portable instrument can be carried and set up 
underground by firefighting and MSHA emergency personnel. Alarms 
warn of dangerous levels of individual gases. Three field-ready 
units were completed and delivered to MSHA in 1980. 



131 



COMPUTER SIMULATION OF MINE ESCAPE ROUTES : The Bureau has devel- 
oped a computer program to evaluate mine evacuation. The mine's 
general layout is represented on a computer by a network akin to 
an electrical circuit diagram, consisting of miner location, 
escape routes, miner walking or climbing, air speed, airflow 
properties, smoke and stench propagation, and hoist speeds, capa- 
cities, and procedures. The location of the fire and self-rescuer 
time limits are set by the user of the program. The simulation 
produces the exact times of various events and plots elements such 
as hoist movements. Summary data include such information as 
total number of miners evacuated, 
miners exposed to smoke, and average 
to evaluate different escape routes, 
ation procedures. Evacuation times 



evacuation times, number of 

smoke exposure, which is used 

hoisting, and various evacu- 

produced by computer simula- 



tion correspond to actual recorded evacuation times. 



^^;^\ 




EV«CUiTION NETIORi; 




RESCUE SHELTERS : In response to the recommendations of the Nation- 
al Academy of Engineering, a project was funded to develop a 
portable mine rescue chamber that would serve as a refuge if 
escape from a mine were not possible in an emergency. Three 
different bulkheads were designed to meet the various emplacement 
requirements of coal mines. The three were erected by miners 
during 1977 in the Bureau's Safety Research Mine to determine the 
cost and the complexity of building rescue chambers, and subse- 
quently tested in the mine against both dust and gas explosions. 
All three bulkheads survived multiple explosions, and, with minor 
design modification to the seals, demonstrated that they could 
provide protection to trapped miners. As a final step in provid- 
ing a total information package to industry, detailed guidelines 
on rescue chamber construction, maintenance, life support, commu- 
nications, first aid, etc., are being developed. 



132 



SUMMARY TABLES 



HealW 



Resf^able Dust. .^ 
Noise., . . . .'x 



^^^ 





^ Irtdu^arn_ 
,%diation. .,^. .^ . .>. , 
if\ccident Prevention- 
Ground Control . . . 






>r-#, 






^» 






■r ' 







jl 



Cfisaster Prevention i 

\ if, 

I Firte and Explosion Prevention. 



•K ^- 



^ 'Explosives ' 176 

Methane Control 1 77 

Postdisaster, Survival, and 

Mine Rescue ''^' 



- -If nil ' 



Introduction 

The following Summary Tables are arranged by 
research area and provide a more extensive insight 
into projects which have had (denoted by *) or are 
expected to have impact within two years (denoted 
by 0) on the industry and on MSHA. Where more 
detailed explanation was warranted this has been 
provided in the preceding sections. The page 
numbers in the Summary Tables refer to the detail- 
ed writeups in Sections II, III, and IV. 



134 



RESPIRABLE DUST 




A. Engineering Controls 

1. Water Systems/Sprays 

a. Nonclogging Water System 

b. Improved Sprays - Ripper 

c. Improved Sprays - Plow 

d. Wet-Head Auger 

e. Water Infusion 

f. Water at Transfer Point 

g. Roadway Additives 

h. Water with Conventional Cut and Drill 

2. Ventilation 

a. Extensible Brattice 

b. Secondary Ventilation 

(1) Auger 

(2) Ripper 

(3) Double Drum Shearer 

(4) Shearer Clearer 



10 
10 

11 



12 

12 



202 
202 
202 
202 
202 
202 

202 

205 

303 

303 
303 
202 
202 



70.100 

70.100 

70.100 

70.100 

70.100 

57.5-4 
70.100 

57.9-74 
70.100 

57.5-4 
75.302 

70.100 
70.100 
70.100 
70.100 



* Completed 

Completed 
Within Two 
Years 



135 



RESPIRABLE DUST 




A. Engineering Controls (continued) 

c. Pressurization System for Process Mills 

d. Bulk Handling 

e. Secondary Ventilation-Transfer Point 

3. Dust Collectors (Scrubbers) 

a. Measure Efficiency 

b. Wetted Fiber Bed 

c. Wetted Fan 

d. Droplet Eliminators for Scrubbers 

e. Twin Scrubber for Continuous Miners 

4. Fragmentation Control 

a. Deep Cutting Ripper 

b. Primary Reduction - Linear Cutting 

5. Process Mill-Bagging Hardware 

a. Secondary Ventilation Shells 

b. Nozzle Cleanout System 

c. Bag Surface Cleaning 

d. Broken Bag Disposal 



14 



14 
11 



13 
13 



205 
205 
202 

202 

202 
202 
202 
202 

202 
202 

205 
205 
205 
205 



57.5-4 
57.5-4 
70.100 

70.100 
70.100 
70.100 
70.100 
70.100 

70.100 
70.100 

57.5-4 
57.5-4 
57.5-4 
57.5-4 



* 



* Completed 

Completed 
Within Two 
Years 



136 



RESPIRABLE DUST 



A. Engineering Controls (continued) 

6. Drill-Dust Capture System 

7. Dust Collector Development 

8. Airborne Dust from Taconite Tailings 

B. Personal Protective Devices 
1. Canopy Air Curtain 

a. Underground Face Equipment 

b. Vehicle Cab 

C. Dust Characterization 

1. Size, Shape, Chemical Characterization 

2. On-Filter Alpha Quartz Analysis 

D. Dust Samplers-Methodology 

1. Statistical Analysis of Samplers 

2. Area Sampling 

3. Light Scattering Dust Monitor 

4. Machine Mounted Dust Monitor 




202 


57.5-2 


202 


57.5-2 


202 


70.201 


202 


70.201 



Completed 

Completed 
Within Two 
Years 



137 




RESPIRABLE DUST 



D. Dust Samplers-Methodology (continued) 

5. Personal Exposure Monitors 

6. Tamper Proof Cassette 

7. Fibrous Aerosol Monitor 



16 



202 


70. 


2 01 


202 


70. 


201 


202 


70. 


201 




57. 


5-4 



* Completed 

Completed 
Within Two 
Years 



138 




NOISE 



A. Noise and Vibration Impact Assessment 



1. Assessment of Whole Body Vibration 
Levels of Miners 



2. Noise Study of Longwall Mining Systems 

B. Criteria for Noise Control Technology 

1. Assessment of Noise Control Techniques 
for Mining Machinery 



2. Demonstration of Techniques to Quiet 
Stoper Drills 

3. Effects of UG Environment and Loading on 
Noise Levels of Mining Equipment 

4. Investigation and Control of Noise 
Generated During Coal Cutting 

5. Noise Attenuating Properties of 
Earmuf f s 



6. Noise Abatement of Vibrating Screens 



19 



19 



24 



501(a) 

501(a) 
501(a) 

501(a) 
501(a) 
501(a) 
501(a) 

501(a) 



55.5-50 
56.5-50 
57.5-50 
71.300 

70.501 



55.5-50 
56.5-50 
57.5-50 
71.300 

57.5-50 
71.300 

57.5-50 
70.501 

70.501 



55.5-50 
56.5-50 
57.5-50 
71.305 

55.5-50 
56.5-50 
71.300 



* Completed 

Completed 
Within Two 
Years 



139 




NOISE 



Criteria for Noise Control Technology (cont.) 



7. Predicting the Screening Performance of 
Nonmetallic Decks 



8. Flammability Evaluation of Noise Control 
Products for Use in Underground Mines 



9. Development of Quiet Resilient Screens 
for Use in Coal Preparation 

10. Fire Hazard Criteria for Noise Control 
Products in Underground Mines 

11. Environmental Testing of Personal 
Audio-Dosimeters 



12. Field Evaluation of Resiliently Clad 
Screen Decks 



13. Noise Control Guidelines for the Mining 
Industry — Handbook 



14. Demonstration of Techniques to Quiet New 
Designs of Jumbo Drills 



24 



25 



21 



501(a) 



501(a) 



501(a) 



501(a) 



206 



501(a) 



501(a) 



501(a) 



55.5-50 
56.5-50 
71.300 

55.5-50 
56.5-50 
57.5-50 
70.501 

70.300 



57.5-50 
70.501 

55.5-50 
56.5-50 
57.5-50 
70.505 

55.5-50 
56.5-50 
57.5-50 
71.300 

55.5-50 
56.5-50 
57.5-50 
71.300 

55.5-50 
57.5-50 



* * 



* Completed 

Completed 
Within Two 
Years 



140 



NOISE 




C. Design Inherently Quieter Equipment 



1. Development of a Reduced Noise Auger 
Miner Cutting Head 

2. Development of Prototype Production Coal 
Mine Stoper Drills 

3. Machine Design Concepts with Application 
to Noise Control of Mining Machinery 



4. Noise Sources and Control Techniques of 
Longwall Mining Systems 

5. Development of Prototype Preproduction 
Jumbo Drill 

6. Development of Prototype Production Hand- 
held Rock Drills for Use in Metal and Non- 
metal Mines (Pneumatic Percussive Drills) 

7. Implementation of State-of-the-Art Noise 
Control Technology into the Design of a 
New Coal Preparation Plant 

8. Noise Control of Underground Load-Haul-Dump 
Machines 

9. Integration of Quieting Technology into 
New Mantrip Vehicles 



21 



18 



501(a) 
501(a) 
501(a) 

501(a) 
501(a) 
501(a) 

501(a) 



70.501 



70.501 



55.5-50 
56.5-50 
57.5-50 
70.501 

70.501 



55.5-50 
57.5-50 

57.5-50 



71.300 



501(a) 


57.5-50 




70.501 


501(a) 


70.501 



o o 



o o 



* Completed 

Completed 
Within Two 
Years 



141 



NOISE 



D. Retrofit Noise Control 

1. Noise Control of Continuous Mining Machines 

2. Stoper Drill Retrofit Noise Control 
Technology 

3. Demonstrating the Noise Control of Coal 
Preparation Plants 

4. Demonstration of Bulldozer Noise Control 



5. Noise Control of Rubber-Tired, Front-End 
Loaders Used in Surface Mining 

6. Mantrip Noise Control 

7. Source Diagnosis and Abatement Techniques 
in Taconite Plants 

8. Demonstration of Noise Control Technology 
for the Crushing and Screening of 
Nonmetallic Minerals 

9. Installation and Evaluation of Crusher 
Noise Control 



10. Auger Miner Retrofit 

11. Silencing the Flame Channeling Process 




23 



22 



18 
23 



23 

20 
22 



501(a) 
501(a) 

501(a) 

501(a) 
501(a) 

501(a) 

501(a) 

501(a) 
501(a) 



57.5-50 
70.501 

71.300 



55.5-50 
56.5-50 
71.300 

55.5-50 
56.5-50 
71.300 

70.501 

57.5-50 



55.5-50 
56.5-50 
57.5-50 

55.5-50 
56.5-50 
57.5-50 

70.501 

55.5-50 
56.5-50 



* Completed 

Completed 
Within Two 
Years 



142 



VENTILATION 




A. Parachute Stopping 



B. Damage Resistant Brattice 



C. Quick-Fix Blowout Stopping 



D. Tear-Resistant Ventilation Tubing 



E. Chilled Water Sprays for Stope Cooling 



F, Induction Ventilation Fans 



G. Forecasting Methane in Oilshale Mines 



H. Using Mine Ventilation to Warn of Incipient 
Fires 

I. Self Seal Brattice for Mine Rescue 
and Recovery 

J. Diffuser Fan Optimization 



K. Spray Fan 



28 



27 



30 



29 



32 



28 



29 



303 



3o: 



303 



303 



303 



303 



303 



303 



303 



303 



57.5 
75.300 

57.5 
75.300 

57.5 
75.300 

57.5 
75.300 

57.5 
75.300 

57.5 
75.300 

57.5 
75.300 

57.5 
75.300 

57.5 
75.316 

75.300 



* Completed 

Completed 
Within Two 
Years 



143 



VENTILATION 




L. The Brattice Window Method for Measurin 
Leakage Across Mine Stoppings 



M. SFg Tracer Gas 



N. Methane Concentration Fluctuations at 
Coal Mine Working Faces 

0. Assessing Methane Buildup Hazards Caused 
by Dust Scrubber Recirculation 

P. Methane Accumulations in Mine Roof 
Cavities 

Q. Accurately Measuring Low Air Velocities 



R. Methane Hazards in Noncoal Mines 

S. New Stopping Sealants 

T. Ventilation of Sealed Gobs 



31 



30 



32 



32 



303 

303 

303 

303 

303 

303 

303 
303 



57.5 
75.300 

57.5 
75.300 

57.5 
75.308 

75.300 



57.5 

57.5 
75.300 

57.5 
75.300 

57.5 

57.5 



* Completed 

Completed 
Within Two 
Years 



144 



INDUSTRIAL HYGIENE 



A. Toxic Products 

1. Mine Combustion Products Identification 
and Analysis 

2. Explosive Fumes from Shotfiring 



3. Survey of Mine Airborne Contaminants 

a. Training Course, Instructors, 
Teaching Guide 

b. Handbooks; Inhalation Contaminants 



4. Monitoring and Measurements 

a. Vacutainer Sampling Technique 

b. Analytical Methods 



c. Passive Personal NO and NO2 
Samplers 

d. Handheld Indicating CO, NO2 , 
and NO Detectors 

e. Evaluation of Gas Detection 
Devices 




* Completed 

Completed 
Within Two 
Years 



145 



INDUSTRIAL HYGIENE 



A. Toxic Products (continued) 

f. Carbon Monoxide Detector Badges 

g. Evaluation Methods for Gas Detection 

h. Monitoring Strategies for Air 
Quality Control 

B. Diesels 

1. CO2 Monitor for Diesels Operated 
Underground 

2. Air-Quality Control for Dieselized Mines 

a. Diesel Exhaust Monitoring 

b. Mine Air Monitoring 

c. Computer Simulation of Contaminant 
Level Distributions 

3. Control of Diesel Engine Exhaust 

a. Evaluation of Diesel Systems 

b. Exhaust Conditioners 

(1) Carbon Bed Absorption of 
Contaminants 




37 



38 



303(b) 



303(b) 
303(b) 

303(b) 

303(b) 
303(b) 
303(b) 

303(b) 

303(b) 



57.5-26 
75.301 

57.5-26 
75.301 

57.5 
75.301 



57.5 

57.5 
57.5 
57.5 



57.5 
75.301 



57.5 
75.301 



* Completed 

Completed 
Within Two 
Years 



146 



INDUSTRIAL HYGIENE 




Diesels (continued) 



(2) Emission Control By Tandem Combi- 
nations of Catalytic Convertors, 
Water Scrubbers, Filters & EGR 

(3) Particulate Trap 



c. Maintenance 



d. Fuels (Onboard Emulsif ication) 



4. Evaluation of Diesel Equipment 

a. Developing Computer Models for 
Contaminants 



38 



303(b) 

303(b) 
303(b) 
303(b) 

303(b) 



57.5 
75.301 



57.5 
75.301 

57.5 
75.301 

57.5 
75.301 



57.5 
75.301 



* Completed 

Completed 
Within Two 
Years 



147 



RADIATION 




A. Instrumentation 

1. Continuous Radiation Monitoring 

2. Radon-Daughter Dosimeter 

3. Personal Alpha Alarm 

4. Remote Working Level Monitor (RWLM) 

B. Control 

1. Radon Control Modeling 

2. Using Classified Mill Tailings 
for Backfilling 

3. Removal of Radon Daughters by Air Cleaning 

4. Uranium Mine Bulkhead Design 

5. Radon Barrier Coatings 

C. Twilight Mine Facility 

D. Radon Sources Surveys 



40 
40 

41 

43 

42 

43 
41 
42 



501(a) 
501(a) 
501(a) 
501(a) 

501(a) 
501(a) 

501(a) 
501(a) 
501(a) 
501(a) 
501(a) 



57.5-37 
57.5-37 
57.5-37 
57.5-38 

57.5-38 
57.5-38 

57.5-38 
57.5-38 
57.5-38 
57.5-38 
57.5-38 



* Completed 

Completed 
Within Two 
Years 



148 



GROUND CONTROL 




A. Premining Investigations 

1. Mining Applications of Surface Seismic 
Techniques 

2. Hazardous Geologic Structures 

3. Delineate Abandoned Mine Workings 

4. Borehole Geophysics 

5. Nondestructive Evaluation Techniques for 
Large Rock Specimens 

6. Guidelines for Mining Near Bodies of Water 

7. Oil and Gas Well Detection 

a. Computerized Mine Layout 

b. Cased Well Detection System 

8. Exploration and Application to Design 

9. Core Book 
10. Catalog of Linear s in Mining Areas 



46 
50 
47 



47 



302(a) 



302(a) 
317(b) 
317(b) 

302(a) 

317(r) 
317(a) 
317(a) 
317(a) 
302(b) 

302(a) 



75.200 



75.200 

75.1701 

75.200 
501(a) 

75.200 

75.1716 

75.1700 

75.1700 

75.1700 

75.200 
75.201 

75.200 



* Completed 

Completed 
Within Two 
Years 



149 



GROUND CONTROL 




B. Selection of Mining Systems and Mine Opening 
Design 

1. Longwall Studies 

a. Coal Mine Single Entry Study 



b. Design of a Single Entry Development 
System for Retreat Mining for Longwall 
Development 

c. Design of Entry Configurations and Ground 
Support for Longwall Panel Development 

d. Support Load Measurements 

e. Plate Bearing Capacity Tests 

f. Strata Movement Measurement 

g. Longwall Support Selection Criteria 

2. Shortwall Mining Demonstration 

3. Physical Properties and Stress Analysis 

a. In Situ Stress Measurements 

b. Coal Pillar Strength Study 

c. In Situ Property Measurements 



54 



52 

55 
50 

53 
48 



501 

501 

302(b) 

501 

302(b) 

302(b) 

302/501 
302/501 
302/501 



302(b) 


75.200 


501(a) 


75,201 




75.326 




75.1704 


302(b) 


75.200 


501(a) 


75.201 




75.326 




75.1709 



75.200 

75.201 
75.201 
75.201 
75.201 

75.201 

75.201 
75.201 
75.201 



* Completed 

Completed 

Within Two 
Years 



150 



lOUND CONTROL 



Selection of Mining Systems and Mine Opening 
Design (continued) 

d. Structural Behavior Study 

e. Constitutive Relations of Coal 

f. Borehole Shear Strength Tester 

4. Bounce and Outburst Study 

5. Design Manual for Room and Pillar Mines 

6. Destressing in Advance of Mining 

7. Blasting Damage Guidelines 
Ground Support Systems and Equipment 

1. Inorganic Grouts for Coal Mine Roof Bolts 

2. Concrete Crib Design and Testing 

3. Modeling Roof Bolting Systems 

4. Coal Mine Rock Reinforcement Study 

5. Mine Roof Presupport by Forepoling 
(Spiling) , Design Feasibility 




48 

51 
61 



57 



302/501 

302/501 

302/501 

501 

301(b) 

301 Cb) 



75.201 

75.201 

75.201 

75.201 

75.201 

57.3-35 

77.1303 



302(a) 


75.200 


302(a) 


75.200 


302(a) 


75.200 


302(a) 


75.200 


302 


75.200 




75.200-1 




75.200-7 




75.200-1: 



o 
* * 



* Completed 

Completed 
Within Two 
Years 



151 



GROUND CONTROL 



C. Ground Support Systems and Equipment (continued) 
6. Flexible Liner in Advancing Tailgate 



7. Chemical Modification of Pumpable Bolt Resin 



>. Fabrication and Testing of a Low Coal Longer- 
Than-Seam-Height Drill 



9. Mine Roof Presupport Field Test 



10. Timber Use and Availability Study 

11. Mine Cribs of Variable Rate of Closure and 
Total Amount of Closure, Est. Start Date FY81 

12. Model Roof Bolt Test System 

13. Longwall Face Stabilization 

14. Longwall Support Testing 




60 



302 
303 
501 



302 



58 
52 
53 



302(b) 
501(a) 



302 



302(a) 
302 

501 
501 
302(b) 



75.200 
70.100 
70.244 
75.301 
75.1704-U 

75.200 

75.200-1 

75.200-7 

75.200-131 

77.1008 

75.200-8 
75.200-7 
75.200-13 
75.200-12 

75.200 
75.200-1 
75.200-7 
75.200-131 

75.200 
75.200 



75.200 
75.200 
75.201 



* Completed 

Completed 
Within Two 
Years 



152 



GROUND CONTROL 



C. Ground Support Systems and Equipment (continued) 

15. Field Evaluation Techniques for Roof Bolt 
Systems 

16. Roof and Rib Sealants 

17. Full Column Resin Bolt Design Criteria 

18. Air Conditioning Chambers 

19. Evaluating Resin Grouted Roof Bolts 

20. Yielding Rock Bolt 

21. Latex-Modified Concrete Lagging 

22. Ground Support for Block Cave Mining 

D. Safe Support Installation and Protection at 
the Face 

1. Retreat Mining Methods 

2. Evaluate Support Wall Systems 



3. Development of Lightweight Hydraulic 
Supports 

4. Evaluation of Mine Roof Bolter Components 




57 
51 
56 

62 
62 



58 



302 (a) 



302(a) 
302(a) 
501 



302 

302 
303 



302(a) 



75.200 



75.200 

75.200 

75.200 

75.200 

57.3-30 

57.3-20 

57.3-30 



40 



75.200 

75.300 

75.200- 

75.201 

75.200 



75.200 



* Completed 

Completed 
Within Two 
Years 



153 



GROUND CONTROL 



D. Safe Support Installation and Protection at 
the Face (continued) 

5. Retreat Mining Support System 



6. Output Torque Indicator for Bolting Machine 

7. Hardened Washers for Uniform Roof Bolt Load 



8. Second Generation Mobile Support for Retreat 
Mining 



9. Operational Techniques for Retreat Mining 



10. Design and Develop Standardized Controls on 
New Roof Machines 

11. Develop Equipment to Expedite the Installa- 
tion of Roof Trusses 




* Completed 

Completed 
Within Two 
Years 



154 



GROUND CONTROL 



D. Safe Support Installation and Protection at 
the Face (continued) 

12. Design, Construct and Mine Test a Device for 
Installing Cement-Grouted Roof Bolts 



13. Roof Bolt Anchorage Quality Indicator/Tension 
Bleed-Off Equalizer 

14. Health and Safety Analysis of Support Walls 

15. Remotely Operated Longwall Head/Tail Supports 

16. Evaluation of Roof Trusses 

17. Remote Manual Controlled Roof Bolter 




18. Application of Weathering Protection on the 
Face 

P 19. Mechanical Scaling Bar 

E. Hazard Detection and Monitoring Systems 
P 1. Rock Bolt Load Cell 

2. Application of Rock-Burst Technology 

3. Development of a Low-Cost Stress Gage 






61 



302(b) 
501(a) 



302(a) 

302 
302(a) 



302(b) 
501(a) 



302(a) 



59 302 



302 
302 
302 



75.200-8 
75.200-7 
75.200-12 
75.200-13 

75.200 



75.200 
75.200 

77.100-8 

75.200-7 

75.200-8 

75.200-12 

75.200-13 

75.200 
75.200 

57.3-22 
57.3-35 
57.3-22 



o o 



■k 



* Completed 

Completed 
Within Two 
Years 



155 



GROUND CONTROL 



E. Hazard Detection and Monitoring Systems (cont.) 

4. High Speed Drill to Detect Abandoned 
Underground Workings 

5. Roof Fall Warning Systems 

6. Rock-Bolt Load Cell 

7. Develop Roof Bolt Tension Indicators 

8. Remote Geophysical Detection from the Face 

9. Infrared Techniques: Loose Rock, Combustion 
Zones, Explosive Misfires, Electrical Shorts, 
and Mine Rescue of Personnel 

10. Borehole Stratascope 

11. Horizontal Roof Strain Indicator (HORSI) 

12. Full Column Resin Bolt Test Device 

13. Magneto-Strictive Borehole Extensometer 

14. Microseismics Applied to Safety 



15. Assessment & In-Place Control of Decay in 
Mine Timber 

16. Improving Surface Coal Disposal Site 
Inspections 




56 



49 



60 



302(f) 
302(a) 
302(d) 
302(a) 
302(b) 

302 
501(a) 



75.205 



501 


75. 


200 


302(d) 


75, 


203 


302(d) 


75. 


203 


501 


75 


205 


302(f) 


75 


205 



75.205 
75.200 
75.203 
75.200 
75.200 

75.200 
77.215 



* Completed 

Completed 
Within Two 
Years 



156 



GROUND CONTROL 




F. Waste Disposal 

1. Rapid Monitoring of Embankment Stability 

2. Electrokinetic Consolidation of Fine Waste 
Material 

3. Pneumatic Backpaking 

4. Coal Waste Embankment Design 

5. Emergency Coal Waste Disposal System Hazard 
Study 



63 



501(a) 



303(a) 
501(a) 

501(a) 

501(a) 

501(a) 



77.215 
77.216 



77.215 
77.215 



* Completed 

Completed 
Within Two 
Years 



157 



INDUSTRIAL HAZARDS 




A. Ergononics (Human Factors) 

1. Environment 

a. Study of Human Engineering and Organiza- 
tional Development in M/NM Mines 

b. Safety-Oriented Supervisory and Manage- 
ment Training Program for UG Mining 

c. Feasibility of Utilizing Employee 
Assistance in Mining Industry 

2. Machine/Work Systems 

a. Research Study of New Methodologies in 
Mine Investigation 

b. Design and Evaluation of Human Engineered 
Work Station for Surface and UG Equipment 

c. Visibility Requirements for Face and 
Mobile Equipment in UG Coal Mining 

d. Human Factors Problem Identification in 
Surface Mining 

e. Investigation of Information Processing 
Demands for Hoist Operators 



65 



501(a) 



502(a) 



501(a) 



501(a) 



501(a) 



501(a) 



501(a) 



501(a) 



57.18 



48. 
57.18 



77.200 



56.19 
75.155 



* Completed 

Completed 
Within Two 
Years 



158 




INDUSTRIAL HAZARDS 



I 



A. Ergononics (Human Factors) (continued) 
3. Miner 

a. Use of Personal Equipment in Low Coal 

b. Biomechanical Study in Low Coal 

c. Cross Validation of Mining Population 
Against Known Anthropometric Data 

d. Biomechanical Study of Work in UG 
M/NM Mines 

e. Cost Indication for Mining Accidents 

f. Computer Simulation 

B. Education and Training 

1. Shuttle Car Training System 

2. Continuous Miner Training System 

3. Mine Hoist Operations Training System 



4. Roof Bolt Equipment Operator Training 
System 



66 
65 



66 



69 



68 



69 



501(a) 
501(a) 
501(a) 

501(a) 

501(a) 
501(a) 

115(a) 

115(a) 
115(a) 
115(a) 



75.705-6 



48. 
75.200 

48. 
75.200 

75.155 
77.105 

48. 



* Completed 

Completed 
Within Two 
Years 



159 



INDUSTRIAL HAZARDS 




B. Education and Training (continued) 

5. Research and Development of New Miner and 
Annual Refresher Training Programs 

6. Development of Baseline Materials for 
Assisting Compliance /Reduction in the 
M/NM Mining Industry 

7. Evaluation and Comparison of Linear and 
Branching Delivery Systems: (a) Electrician; 
(b) Blasting 

8. Investigation and Development of Training 
Programs for Shaft Sinking Personnel 

9. Training Programs for Shaft Sinking Person- 
nel in Compliance with Proposed Regulations 

10. Development of Requisite Support for the 
Lincoln Training Systems 

11. Evaluation of Stand-Alone, Interactive 
Teaching Machines for Mine Vocational 
Training 

12. Improvement of On-the-Job Training Through 
Modeling Imitative and Vicarious Learning 
Techniques 

13. Demonstration of an In-Mine Training 
Enhancement and Communication System 



70 



115(a) 
115(a) 

115(a) 

115(a) 
115(a) 
115(a) 
115(a) 

115(a) 

115(a) 



48. 



48. 

75.160 

75.200 

75.160 



75.160 



48. 



48. 

75.160 

75.200 

48. 

75.160 

75.200 

48. 
75.200 



* Completed 

Completed 
Within Two 
Years 



160 



INDUSTRIAL HAZARDS 



B. Education and Training (continued) 

14. Standards for Mine Equipment Design/ 
Investigation of Improved Methods /Media 
for Off-the-Job Operator Training 

15 . Study to Determine the Manpower and Training 
Needs of the Coal Mining Industry 

16. Pre-Shift Inspection Procedures for Surface 
Mining Equipment 

17. Haulage Truck Training System 



18. Front-End Loader Training System 

19. Benefit/Cost Model for Safety Training 
Programs 

20. Safety Training Evaluations 

21. Safety. . .Let's Make it Happen 

22. Training Programs for Mine Rescue Teams 

23. Review and Evaluation of Current Training 
Programs 

24. Training Program for Fighting Small Fires 




* Completed 

Completed 
Within Two 
Years 



161 



INDUSTRIAL HAZARDS 




C. Electrical 

1. Power Distribution 

a. Power System Measurement 

b. Transients Measurements 

c. Surge Capacitor Analysis 

d. High Voltage Proximity Warning Device 

e. Power System Simulator 

f. Continuous Safety Monitor System 

g. Periodic Inspection Methods 

h. Reference Manual, Power Systems 

i. Application Notes, Power Systems 

j. Minerals Processing Power 

2. Cables 

a. Cable Ratings 

b. Cable Reel Application Factors 



70 



75 



75 
71 



308 
309 

308 
309 

308 
309 



501(a) 
501(a) 
501(a) 

305- 
310 

305- 
310 



306 



306 



57.12 
75(F) 

57.12 
75(F) 

57.12 
75(F) 

77.807-2 

75.518 

75(F,G) 

75(F,G) 

75(F,G) 

75(F,G) 

77.506-1 



18.35 
18.36 

18.45 



* Completed 

Completed 
Within Two 
Years 



162 



INDUSTRIAL HAZARDS 




C. Electrical (continued) 

3. Trailing Cable Splices 

a. Splice Techniques and Approval Standards 

b. Splice Adhesives and Insulation 

c. Crimp Sleeve Design 

4. Trailing Cable Fault Locators 

a. Infrared Fault Locator 

b. Time Domain Ref lectometer 

c. Frequency Domain Ref lectometer 

d. Audio Frequency Fault Locators 

5. Trolley Line Power 

a. Discriminating Circuit Breaker System 

b. Vapor Phase Switch for High Level D.C. 

c. D.C. Circuit Breaker Portable Calibrator 

d. Remote Control CRT Breaker System 



72 



73 



74 



306(d) 
306(d) 
306(d) 



306 
307 

306 
307 

306 
307 

306 
307 



310(b) 
310(b) 
310(b) 
501(a) 



75.604 
75.604 
75.604 



75.604 
75.902 

75.604 
75.902 

75.604 
75.902 

75.604 
75.902 



75.1001 
75.1001 
75.512 
75.1600 



o 



* Completed 

Completed 
Within Two 
Years 



163 




INDUSTRIAL HAZARDS 



C. Electrical (continued) 

6. Circuit Protection Devices 

a. Ground Fault and Overcurrent Protection 



b. Shock Prevention by High Sensitivity 
Fault Protection 

c. Reliability of Protective Devices 

7. Permissibility 

a. Pressure Vent 

b. Performance Standards 

D. Equipment 

1. Underground Operator Protective Structures 

a. Advancement of Cab and Canopy Design and 
Use in Coal Mines 

b. Development and Assessment of New and 
Existing Canopy Technology to Lower 
Coal Seams 

c. Automatic Steering Low Coal Shuttle Car 

d. Demonstration and Extension of Existing 
Canopy Technology to Lower Coal Seams 



73 

74 

74 



71 



76 



76 



309 



501(a) 



305 
305 



301(b) 



301(b) 75.1710 



301(b) 
301(b) 



75.518 
75.601 
77.600 

75.524 



501(a) 75.518 



18 

18 



75.1710 



75.1710 
75.1710 



* Completed 

Completed 
Within Two 
Years 



164 



INDUSTRIAL HAZARDS 



D. Equipment (continued) 

e. Feasibility of Providing Adequate Human 
Engineered Operator's Cabs in Thin Seams 
Using a Remotely Positioned Operator 

f. Extension of Low Coal Canopy Technology 

2. Mobile Equipment Brakes 

a. Portable Dynamic Brake Testing Apparatus 
for Mobile Underground Mine Equipment 

b. Equipment Development 

c. Design of New Railroad Truck Assemblies 
for Underground Coal Mine Cars 

3. Improved Operator Controls 

a. Second Generation Stability Indicator 
for Front End Loaders 

4. Innovative Equipment Design 

a. Fabrication of a Low Vein Circular Kerf 
Cutting Machine 

b. Underground Utility Vehicle 



c. Improved Visibility Systems for Large 
Haulage Trucks 




- - * Completed 

Completed 
Within Two 
Years 



165 



INDUSTRIAL HAZARDS 




D. Equipment (continued) 

d. Improved Haulage Truck Ladders 

e. ROPS Performance Criteria 

f. Equipment Safety Analysis 

g. Airline Linking Components 

E . I lluminat ion 

1. Demonstrations 



a. Illumination of a Conventional Slope 
Under Construction 

b. Demonstration of Coal Mine Illumination 
Systems (Continuous and Conventional 
Mining Machines) 

c. Demonstration of Coal Mine Illumination 
Systems (Problem Areas) 

d. Factory Integration of Illumination 
Systems into Mining Machinery 

e. Factory Integration of an Illumination 
System into a Thin Seam Scoop 

f. Demonstration of Coal Mine Illumination 
Systems (Hardware Development) 

g. Illumination System on Continuous Miners 
in Trona Extraction 



78 
80 



83 
84 



85 



301(b) 
301(b) 



55.9-J 
77.1606 



317(e) 
317(e) 

317(e) 
317(e) 



57.17 
75.1719 

75.1719 



75.1719 



57.17 
75.1719 



317(e) 75.1719 



317(e) 



75.1719 
57.17 



o 



I 



* Completed 

Completed 
Within Two 
Years 



166 




INDUSTRIAL HAZARDS 



E. Illumination (continued) 

h. Illumination of Electric Powered Mobile 
Surface Mining Machinery (Large Draglines 
and Shovels) 

i. Illumination of Electric Powered Mobile 
Surface Mining Machinery (Small Draglines) 

j. Shortwall Illumination System 

2. Basic Studies 

a. Development of Guidelines for Installation 
and Maintenance of Mine Illumination 
Systems 

b. Psychophysical Investigations of Disability 
and Discomfort Glare from Underground Mine 
Illumination Systems 

c. An Interactive Computer System for 
Evaluating Mine Illumination 

d. An Analysis of Work Areas and Tasks to 
Establish Illumination Needs for M/NM 
Mines 

e. Computer Evaluation of Surface Mine 
Illumination Systems 

3. Hardware Development 

a. Development of Low Glare Illumination 

Systems for Thin Seam Coal Mine Equipment 



85 
83 



81 



317(e) 

317(e) 
317(e) 

317(e) 
317(e) 
317(e) 



317(e) 



317(e) 



55.17 
77.207 



55.17 
77.207 

75.1719 



57.17 
75.1719 

57.17 
75.1719 



57.17 
75.1719 

57.17 



55.17 



75.1719 



* Completed 

Completed 
Within Two 
Years 



167 



INDUSTRIAL HAZARDS 



E. Illumination (continued) 

b. Development of an Improved Miner's Caplamp 
System 

c. High Intensity Discharge Lamp Ballasts 

for Diesel Powered Surface Mining Equipment 

d. D.C. Power Supplies 



e. Keep Alive Mercury Mine Lighting System 
F. Communications 
1. Hardware 

a. Optical Paging Systems 

b. Multiplexed Telephone Systems 

c. Fiber Optics Systems 

d. Multiplexed Distribution Systems 

e. Selectable Pagerphones 

f. Medium Frequency Systems 

g. Hoist Signalling Systems 

h. Automatic Vehicle Location Systems 




86 
82 
86 

89 



89 



317(d) 



317(e) 
317(e) 
317(e) 

501(a) 
501(a) 
501(a) 
501(a) 
501(a) 
501(a) 

314 Cd) 

501(a) 



75.1719 



55.17 
77.207 

55.17 
77.207 

75.1719 



57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.19-90 
57.9-35 



* Completed 

Completed 
Within Two 
Years 



168 



■■ 



INDUSTRIAL HAZARDS 



W. Communications (continued) 

2. Guidelines, Basic Research 

a. Manual for Mine Communications 

b. Medium Frequency Propagation Analysis 

c. Investigation of EM Fields in Mines 

d. Evaluation of Buried Cable Systems 

e. Demonstration of Carrier Phone Guidelines 

f. Evaluation of Leaky Feeder Systems 

3. Systems 

a. Passive Reflector UHF System Demonstration 

b. Demonstration of Telephone Systems in 
Deep Mines 

4. Other 

a. lst-5th Coal Electrotechnology Conference 

b. 1st M/NM Electrotechnology Conference 



90 




501(a) 
501(a) 

501(a) 
501(a) 



75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 

57.20-32 
75.1600 



57.20-32 
75.1600 

57.11-54 



* Completed 

Completed 
Within Two 
Years 



169 



INDUSTRIAL HAZARDS 




F. Communications (continued) 
5. Monitoring 

a. Systems Engineering 

b. Hardware Development 



G. Hoisting 

1. Development of Consistent Low G Arrestment 
Devices 



2. Hoisting System Components-Selection and 
Guidelines 

3. Development of a Fail Safe Slack/Overload 
Rope Protection System 

4. Non-Destructive Testing for Wire Rope 
Retirement 



5. Wire Rope Testing Facility 



6. Wire Rope Fatigue Testing Machine 



90 



92 



91 



92 



93 



303 
303 

314(a) 

314(a) 

314(a,b) 

501(a) 

501(a) 

501(a) 



57.5-26 
75.301 

57.5-26 
75.301 



57.19 

75.1400 

77.1905 

57.19 
75.1400 

57.19 
75.1401 

57.19 

75.1401 

77.1402 

57.19 

75.1401 

77.1402 

57.19 

75.1401 

77.1402 



* Completed 

Completed 
Within Two 
Years 



170 



INDUSTRIAL HAZARDS 




G. Hoisting (continued) 

7. Wire Rope Horizontal Tensile/Axial Fatigue 
Testing Machine 



8. Wire Rope Retirement Criteria and Procedures 

9. Theoretical and Statistical Analysis of Wire 
Rope 

10. Inspection Procedures for Shaft Equipment 

H. Haulage and Materials Handling 

1. Improving Man Transit Safety 

2. Materials Handling Equipment Development 



3. System for Handling Supplies in Underground 
Mines 

4. Alternate Energy Powered Haulage Vehicle 

5 . Develop and Demonstrate a Maintenance and 
Material Handling Vehicle 

6. Develop a Safer, Clean-Out Method 



91 



93 



501(a) 



314(c) 
314(c) 
314(a) 

314(e) 

501(a) 

314(b) 

314(b) 
314(b) 

501(a) 



57.19 

75.1401 

77.1402 

57.19 
75.1401 

57.19 
75.1401 

57.19 
75.1400 



57.9 
75.1403 

57.16 
75.1403 

57.16 
75.1403 



57.16 
75.1403 

57.16 
77.1607 



* Completed 

Completed 
Within Two 
Years 



171 



INDUSTRIAL HAZARDS 



H. Haulage and Materials Handling (continued) 

7. Belt Dressing Applicator 

8. Pneumatic Conveying Studies 

9. Haulroad Berm, Guardrail and Sign Study 




80 



78 
94 



501(a) 



501(a) 

501(a) 



55.14-34 
77.406 



55.9 
77.1605 



* Completed 

Completed 
Within Two 
Years 



172 




FIRE AND EXPLOSION PREVENTION 



A. Ignition Research 

1. Intrinsically Safe Equipment 
I 2. Spontaneous Heating of Coal 

3. Quenching Diameters, Coal Dust-Air 

4. Frictional Ignition 

5. Safe Electrical Insulations Within 
Explosion-Proof Enclosures 

B. Flame Propagation Research 

1. Incombustible Requirements 

2. Explosion-Proof Seals 

3. Accident Analysis for MSHA 

4. Dust Flammability Studies 

5. Scanning Electron Microscope Studies of Dust 

6. Fire Resistant Conveyor Belts 

7. Fire Resistant Hydraulic Fluids 



97 



99 



100 
101 

103 
108 

108 
104 

104 



305 


18.68 


305 


18.23 


501(a) 


18.31 


301(b) 


75.302 


305 


18.25 



304(d) 

303(z) 
501(a) 

103 

304 
501 



304 
311(h) 

311(e) 



75.402 
75.329 



75.202 
75.400 
75.1709 

75.400 

57.4 
75.1108 

57.4 
75.1107 



* Completed 

Completed 
Within Two 
Years 



173 




FIRE AND EXPLOSION PREVENTION 



B. Flame Propagation Research (continued) 

8. Coal Mine Dust Incombustibles Meter 

9. Fire Hazards of Mine Timbers 

10. Remote Dust Deposition Meter 

11. Evaluation of Fire Doors, Air Doors, 
and Bulkheads 

12. Fire and Explosion Hazards of Oil Shale 

C. Fire and Explosion Detection 

1. Pneumatic Fire Detection 

2. Detection or Equivalency in a Ventilated 
Passageway 

3. Particulate Detection in a Sealed Fire 
Area 

4. Selective Submicron Particulate Detection 

5. Improved Underground M/NM Fire 
Protection Hardware 

6. Improved Methane Monitors 

7. Anemometer Calibration Facility 



109 

107 



103 

97 

98 

102 

99 

110 

106 
107 



304(d) 

311 

304(d) 

311 

311 

311(g) 

303 
311 

311 

311 

311 
303 



75.403 

57.4 

75.403 



57.4 



57.4 
75.1103 

75.1103 



57.4 

75.300 

75.1103 

57.4 
75.1103 

57.4 



75.1103 

57.5 
75.300 



* Completed 

Completed 
Within Two 
Years 



174 




FIRE AND EXPLOSION PREVENTION 



D. Suppression and Extinguishment 

1. Remote Sealing of Mine Fires 

2. Sealed Mine Fires 

3. Hybrid Extinguishing Agents 



I 



4. Ignition Quenching Device 

5. Passive Barriers 

6. Triggered Barriers 

7. Fire Control Systems for Mobile 
Equipment 

8. Enclosed Equipment Fire Control 

9. Underground Fueling Area Fire 
Protection Systems 

10. Shaft Fire and Smoke Protection 



E. Escape and Rescue Measures 
1. Mine (Fire) Ventilation 

F. Test Facilities 



102 
101 



100 



105 
106 

105 

110 
109 



98 
111 



103(*) 
103 (k) 

301 (b) 

311 

317(q) 

304 
501(a) 

304 
501(a) 

501(a) 



311(a) 
311(a) 
311(a) 

303 
501(a) 



75.1100 

75.1100 

57.4 
75.1100 

75.302 

75.400 

75.400 

55.9 
57.4 
77.1108 

55.4 
77.1108 

57.4 

57.4 
75.1100 

57.11 



* Completed 

Completed 
Within Two 
Years 



175 



EXPLOSIVES 



A. Blasting Agents and Other Hazardous Chemicals 

1. Development of Safer Permissible Explosives 

2. Barriers and Containers 



3. Alternative to Kelly Bar Loading of Blastholes 

4. Estimation of Maximum Range of Flyrock 



5. Evaluation of Electrical Storm Warning 
Systems 

6. Toxic Gases from Materials Used in 
Underground Mining 



7. Toxic Gases from Explosives 

8. Development of Safer Detonators 

9. Classification of Hazardous Materials 

10. Explosive Identification 




116 
115 

113 
114 

114 
36 

36 
113 
116 

115 



313(c) 
313(f) 

101(a) 
101(a) 

101(a) 
101(a) 

101(a) 
313(c) 
101(a) 

103(a) 



55.6-40 
56.6-40 
57.6-40 

56.6-142 

55.6-160 
56.6-160 
57.6-160 

55.6-124 
56.6-124 
57.6-124 

55.5-1 
56.5-1 
57.5-1 

15.12(f) 



55.6 
56.6 
57.6 

75.1303 



* Completed 

Completed 
Within Two 
Years 



176 



METHANE CONTROL 



A. Measuring and Forecasting the Methane 
Content of Coalbeds 

1. Geologic Studies to Evaluate the Gassy 
Nature of Coalbeds 

2. Direct Method of Determining the Gas 
Content of Coalbeds 

3. Geologic Studies to Evaluate the Gassy- 
Nature of Metal/Nonmetal Mines 

B. Methane Drainage in Advance of Mining 

1. Methane Drainage from Vertical Boreholes 

2. Methane Hydraulic Stimulation Techniques 

3. Methane Drainage Through Shafts 

a. Multipurpose Borehole 

b . Honey Run Shaft 

c. Maple Meadow Mine Shaft 
C. Methane Control During Mining 

1. Gas Drainage in an Advancing Section 

2. Water Infusion 

3. Grouting Horizontal Drainage Holes 




118 



119 



125 



119 
120 
120 



121 
121 

123 



301(b) 



301(b) 



301(b) 



75.316 



75.316 



57.5 



301(b) 75.308 



301(b) 

301(b) 
301(b) 
301(b) 

301(b) 

301(b) 
303 

301(b) 



75.308 

75.308 
75.308 
75.308 

75.308 
75.308 

75.308 



* Completed 

Completed 
Within Two 
Years 



177 



METHANE CONTROL 



C. Methane Control During Mining (continued) 

4. Gob Drainage 

a. Vertical Boreholes 

b. Cross Measure Drainage Holes 

5. Plugging Oil and Gas Wells 

D. Horizontal Drilling and Drainage Technology 
1. Drilling Equipment and Techniques 



2. Electronic Surveying for Horizontal Drilling 

3. Prediction of Coalbed Discontinuities 
A. Underground Methane Pipelines 

5. Electronic Methane Monitoring of 
Underground Pipelines 




* Completed 

Completed 
Within Two 
Years 



178 



POSTDISASTER, SURVIVAL, AND MINE RESCUE 




A. Survival 

1. Oxygen Self Rescuers 

a. 10-Minute Oxygen Self Rescuer 

b. 60-Minute Oxygen Self Rescuer 

c. 10/ 60-Minute Oxygen Self Rescuer 



d. Improved Oxygen Sources for Breathing 
Apparatus 

e. Compressed O2 Self Rescuer 



f. Guidelines for O2 Self Rescuers 



2. Rescue Shelters 



3. Developing New Person Tests for Escape 
and Rescue Apparatus 

4. Automated Breathing Metabolic Simulator 



127 



132 
128 



501(a) 

501(a) 

501(a) 

501(a) 

501(a) 

501(a) 
315 

501(a) 
501(a) 



57.15 
75.1714 

57.15 
75.1714 

57.15 
75.1714 

57.15 
75.1714 

57.15 
75.1714 

57.15 
75.1714 

57.15 
75.1500 

57.15 
75.1714 

57.15 
75.1714 



* Completed 

Completed 
Within Two 
Years 



179 




POSTDISASTER, SURVIVAL, AND MINE RESCUE 



B. Communications 

1. Trapped Miner Location Hardware 

a. Reliability Study of EM Hardware 

b. Development of EM Hardware 

c. Delayed Speech System 

d. Hoist Radio System 

2. Basic Studies 

a. Autodetection Algorithm for Seismic 
Systems 

b. Theoretical Investigation of Seismic 
Waves 

c. Statistical Studies of Fatalities 

d. Technical Analysis of EM Propogation Data 

e. EM Retransmission System 

f. EM System for Deep Mines 

g. Time-Bandwidth Studies of EM Systems 



129 
129 

130 

129 
129 



501(a) 
501(a) 
501(a) 
501(a) 

501(a) 

501(a) 

501(a) 
501(a) 
501(a) 
501(a) 
501(a) 



75.325 
75.325 
75.325 
75.325 

75.325 

75.325 

75.325 
75.325 
75.325 
75.325 
75.325 



* Completed 

Completed 
Within Two 
Years 



180 




POSTDISASTER, SURVIVAL, AND MINE RESCUE 



C. Rescue and Recovery 

1. Acoustic Borehole Probes 

2. TV, Sampling Probes, and Gas Analysis 

3. Lightweight 4-Hour Rescue Breathing Apparatus 

4. Rescue Team Helmet 

5. Advanced Cooling Garment Design 

a. Liquid Cooled Garment 

b. Ice Vest 

6. Escape Hoist Guidelines 

7. Anthropometric Measurement for Face 
Piece Fit 

8. Physiological Responses to Use of 
Breathing Apparatus 

9. Mine Fire Gas Analyzer 

10. Probe and Rescue Drill System 

11. Computer Simulation of Mine Escape Plans 



130 
130 



128 



131 



131 
130 
132 



501(a) 
501(a) 
501(a) 
501(a) 



501(a) 



501(a) 



501(a) 



75.325 
75.325 
75.1714 
75.325 



501(a) 


75.325 


501(a) 


75.325 


314(a) 


57.19 




75.1704 



75.325 



75.325 



501(a) 75.325 



75.325 
57-18-1 



* Completed 

Completed 
Within Two 
Years 



181 



H 94 8 2.«i| 



Created in 1849, the Department of the Interior — 
America's Department of Natural Resources — is 
concerned with the management, conservation, and 
development of the Nation's water, wildlife, 
mineral, forest, and park and recreational re- 
sources. It also has major responsibilities for 
Indian and Territorial affairs. 

As the Nation's principal conservation agency, the 
Department works to assure that nonrenewable 
resources are developed and used wisely, that 
parks and recreational resources are conserved for 
the future, and that renewable resources make 
their full contribution to the progress, prosper- 
ity, and security of the United States — now and 
in the future. 






....-,/ -o,.-^-?'.o' V^-.y %-^\o'> -V.-^^-'.*^* -- • 
















Svp„ 



iV^^ 



0^ ^ *7V^, ^ ^^ 















.,-?>■ t 



^"-n^. 




/.•^.:.*°o .**,c;2^.\ c.°*.i^:."°o 
' V^?^\/ V^^"^^'_A°'' X^*o^'\^^'' %r^^^'\<^' "v"^^"?^'* .^^^ "o. ':^ir^\,o^ -^. 
















-s-^ 










4 o 




^"-n^. 





4 o 











^ ^ '■(Ass A '^o <^^ * Si^3 • ^ ^ '^(CCvssA "^o 'v*' * SiiSa * ^ ■A^ '■rfCCssA "<n^ <^ * SflS^ " ^ <v * 








0° .'^> °o 












